aboutsummaryrefslogtreecommitdiff
path: root/docs/markdown/Rewriter.md
blob: 641448007f83ad0c2ac569df4f6d613c22a84e00 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
---
short-description: Automatic modification of the build system files
...

# Meson file rewriter

Since version 0.50.0, meson has the functionality to perform some basic
modification on the `meson.build` files from the command line. The currently
supported operations are:

- For build targets:
  - Add/Remove source files
  - Add/Remove targets
  - Modify a select set of kwargs
  - Print some JSON information
- For dependencies:
  - Modify a select set of kwargs
- For the project function:
  - Modify a select set of kwargs
  - Modify the default options list

The rewriter has both, a normal command line interface and a "script mode". The
normal CLI is mostly designed for everyday use. The "script mode", on the
other hand, is meant to be used by external programs (IDEs, graphical
frontends, etc.)

The rewriter itself is considered stable, however the user interface and the
"script mode" API might change in the future. These changes may also break
backwards comaptibility to older releases.

We are also open to suggestions for API improvements.

## Using the rewriter

All rewriter functions are accessed via `meson rewrite`. The meson rewriter
assumes that it is run inside the project root directory. If this isn't the
case, use `--sourcedir` to specify the actual project source directory.

### Adding and removing sources

The most common operations will probably be the adding and removing of source
files to a build target. This can be easily done with:

```bash
meson rewrite target <target name/id> {add/rm} [list of sources]
```

For instance, given the following example

```meson
src = ['main.cpp', 'fileA.cpp']

exe1 = executable('testExe', src)
```

the source `fileB.cpp` can be added with:

```bash
meson rewrite target testExe add fileB.cpp
```

After executing this command, the new `meson.build` will look like this:

```meson
src = ['main.cpp', 'fileA.cpp', 'fileB.cpp']

exe1 = executable('testExe', src)
```

In this case, `exe1` could also have been used for the target name. This is
possible because the rewriter also searches for assignments and unique meson
IDs, which can be acquired with introspection. If there are multiple targets
with the same name, meson will do nothing and print an error message.

For more information see the help output of the rewriter target command.

### Setting the project version

It is also possible to set kwargs of specific functions with the rewriter. The
general command for setting or removing kwargs is:

```bash
meson rewrite kwargs {set/delete} <function type> <function ID> <key1> <value1> <key2> <value2> ...
```

For instance, setting the project version can be achieved with this command:

```bash
meson rewrite kwargs set project / version 1.0.0
```

Currently, only the following function types are supported:

- dependency
- target (any build target, the function ID is the target name/ID)
- project (the function ID must be `/` since project() can only be called once)

For more information see the help output of the rewrite kwargs command.

### Setting the project default options

For setting and deleting default options, use the following command:

```bash
meson rewrite default-options {set/delete} <opt1> <value1> <opt2> <value2> ...
```

## Limitations

Rewriting a meson file is not guaranteed to keep the indentation of the modified
functions. Additionally, comments inside a modified statement will be removed.
Furthermore, all source files will be sorted alphabetically.

For instance adding `e.c` to srcs in the following code

```meson
# Important comment

srcs = [
'a.c', 'c.c', 'f.c',
# something important about b
       'b.c', 'd.c', 'g.c'
]

# COMMENT
```

would result in the following code:

```meson
# Important comment

srcs = [
  'a.c',
  'b.c',
  'c.c',
  'd.c',
  'e.c',
  'f.c',
  'g.c'
]

# COMMENT
```

## Using the "script mode"

The "script mode" should be the preferred API for third party programs, since
it offers more flexibility and higher API stability. The "scripts" are stored
in JSON format and executed with `meson rewrite command <JSON file or string>`.

The JSON format is defined as follows:

```json
[
  {
    "type": "function to execute",
    ...
  }, {
    "type": "other function",
    ...
  },
  ...
]
```

Each object in the main array must have a `type` entry which specifies which
function should be executed.

Currently, the following functions are supported:

- target
- kwargs
- default_options

### Target modification format

The format for the type `target` is defined as follows:

```json
{
  "type": "target",
  "target": "target ID/name/assignment variable",
  "operation": "one of ['src_add', 'src_rm', 'target_rm', 'target_add', 'info']",
  "sources": ["list", "of", "source", "files", "to", "add, remove"],
  "subdir": "subdir where the new target should be added (only has an effect for operation 'tgt_add')",
  "target_type": "function name of the new target -- same as in the CLI (only has an effect for operation 'tgt_add')"
}
```

The keys `sources`, `subdir` and `target_type` are optional.

### kwargs modification format

The format for the type `target` is defined as follows:

```json
{
  "type": "kwargs",
  "function": "one of ['dependency', 'target', 'project']",
  "id": "function ID",
  "operation": "one of ['set', 'delete', 'add', 'remove', 'remove_regex', 'info']",
  "kwargs": {
    "key1": "value1",
    "key2": "value2",
    ...
  }
}
```

### Default options modification format

The format for the type `default_options` is defined as follows:

```json
{
  "type": "default_options",
  "operation": "one of ['set', 'delete']",
  "options": {
    "opt1": "value1",
    "opt2": "value2",
    ...
  }
}
```

For operation `delete`, the values of the `options` can be anything (including `null`)

## Extracting information

The rewriter also offers operation `info` for the types `target` and `kwargs`.
When this operation is used, meson will print a JSON dump to stderr, containing
all available information to the rewriter about the build target / function
kwargs in question.

The output format is currently experimental and may change in the future.
f='#n585'>585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248
# Copyright 2012-2015 The Meson development team

# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at

#     http://www.apache.org/licenses/LICENSE-2.0

# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import mparser
import environment
import coredata
import dependencies
import mlog
import build
import optinterpreter
import wrap
import mesonlib
import os, sys, platform, subprocess, shutil, uuid, re
from functools import wraps

import importlib

class InterpreterException(coredata.MesonException):
    pass

class InvalidCode(InterpreterException):
    pass

class InvalidArguments(InterpreterException):
    pass

# Decorators for method calls.

def check_stringlist(a, msg='Arguments must be strings.'):
    if not isinstance(a, list):
        mlog.debug('Not a list:', str(a))
        raise InvalidArguments('Argument not a list.')
    if not all(isinstance(s, str) for s in a):
        mlog.debug('Element not a string:', str(a))
        raise InvalidArguments(msg)

def noPosargs(f):
    @wraps(f)
    def wrapped(self, node, args, kwargs):
        if len(args) != 0:
            raise InvalidArguments('Function does not take positional arguments.')
        return f(self, node, args, kwargs)
    return wrapped

def noKwargs(f):
    @wraps(f)
    def wrapped(self, node, args, kwargs):
        if len(kwargs) != 0:
            raise InvalidArguments('Function does not take keyword arguments.')
        return f(self, node, args, kwargs)
    return wrapped

def stringArgs(f):
    @wraps(f)
    def wrapped(self, node, args, kwargs):
        assert(isinstance(args, list))
        check_stringlist(args)
        return f(self, node, args, kwargs)
    return wrapped

def stringifyUserArguments(args):
    if isinstance(args, list):
        return '[%s]' % ', '.join([stringifyUserArguments(x) for x in args])
    elif isinstance(args, int):
        return str(args)
    elif isinstance(args, str):
        return "'%s'" % args
    raise InvalidArguments('Function accepts only strings, integers, lists and lists thereof.')

class InterpreterObject():
    def __init__(self):
        self.methods = {}

    def method_call(self, method_name, args, kwargs):
        if method_name in self.methods:
            return self.methods[method_name](args, kwargs)
        raise InvalidCode('Unknown method "%s" in object.' % method_name)

class TryRunResultHolder(InterpreterObject):
    def __init__(self, res):
        super().__init__()
        self.res = res
        self.methods.update({'returncode' : self.returncode_method,
                             'compiled' : self.compiled_method,
                             'stdout' : self.stdout_method,
                             'stderr' : self.stderr_method,
                            })

    def returncode_method(self, args, kwargs):
        return self.res.returncode

    def compiled_method(self, args, kwargs):
        return self.res.compiled

    def stdout_method(self, args, kwargs):
        return self.res.stdout

    def stderr_method(self, args, kwargs):
        return self.res.stderr

class RunProcess(InterpreterObject):

    def __init__(self, command_array, source_dir, build_dir, subdir, in_builddir=False):
        super().__init__()
        pc = self.run_command(command_array, source_dir, build_dir, subdir, in_builddir)
        (stdout, stderr) = pc.communicate()
        self.returncode = pc.returncode
        self.stdout = stdout.decode().replace('\r\n', '\n')
        self.stderr = stderr.decode().replace('\r\n', '\n')
        self.methods.update({'returncode' : self.returncode_method,
                             'stdout' : self.stdout_method,
                             'stderr' : self.stderr_method,
                            })

    def run_command(self, command_array, source_dir, build_dir, subdir, in_builddir):
        cmd_name = command_array[0]
        env = {'MESON_SOURCE_ROOT' : source_dir,
               'MESON_BUILD_ROOT' : build_dir,
               'MESON_SUBDIR' : subdir}
        if in_builddir:
            cwd = os.path.join(build_dir, subdir)
        else:
            cwd = os.path.join(source_dir, subdir)
        child_env = os.environ.copy()
        child_env.update(env)
        try:
            return subprocess.Popen(command_array, stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                                    env=child_env, cwd=cwd)
        except FileNotFoundError:
            pass
        # Was not a command, is a program in path?
        exe = shutil.which(cmd_name)
        if exe is not None:
            command_array = [exe] + command_array[1:]
            return subprocess.Popen(command_array, stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                                    env=child_env, cwd=cwd)
        # No? Maybe it is a script in the source tree.
        fullpath = os.path.join(source_dir, subdir, cmd_name)
        command_array = [fullpath] + command_array[1:]
        try:
            return subprocess.Popen(command_array, stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                                    env=child_env, cwd=cwd)
        except FileNotFoundError:
            raise InterpreterException('Could not execute command "%s".' % cmd_name)

    def returncode_method(self, args, kwargs):
        return self.returncode

    def stdout_method(self, args, kwargs):
        return self.stdout

    def stderr_method(self, args, kwargs):
        return self.stderr

class ConfigureFileHolder(InterpreterObject):

    def __init__(self, subdir, sourcename, targetname, configuration_data):
        InterpreterObject.__init__(self)
        self.held_object = build.ConfigureFile(subdir, sourcename, targetname, configuration_data)

class ConfigurationDataHolder(InterpreterObject):
    def __init__(self):
        super().__init__()
        self.used = False # These objects become immutable after use in configure_file.
        self.held_object = build.ConfigurationData()
        self.methods.update({'set': self.set_method,
                             'set10': self.set10_method,
                             'has' : self.has_method,
                            })

    def is_used(self):
        return self.used

    def mark_used(self):
        self.used = True

    def validate_args(self, args):
        if len(args) != 2:
            raise InterpreterException("Configuration set requires 2 arguments.")
        if self.used:
            raise InterpreterException("Can not set values on configuration object that has been used.")
        name = args[0]
        val = args[1]
        if not isinstance(name, str):
            raise InterpreterException("First argument to set must be a string.")
        return (name, val)

    def set_method(self, args, kwargs):
        (name, val) = self.validate_args(args)
        self.held_object.values[name] = val

    def set10_method(self, args, kwargs):
        (name, val) = self.validate_args(args)
        if val:
            self.held_object.values[name] = 1
        else:
            self.held_object.values[name] = 0

    def has_method(self, args, kwargs):
        return args[0] in self.held_object.values

    def get(self, name):
        return self.held_object.values[name]

    def keys(self):
        return self.held_object.values.keys()

# Interpreter objects can not be pickled so we must have
# these wrappers.

class DependencyHolder(InterpreterObject):
    def __init__(self, dep):
        InterpreterObject.__init__(self)
        self.held_object = dep
        self.methods.update({'found' : self.found_method})

    def found_method(self, args, kwargs):
        return self.held_object.found()

class InternalDependencyHolder(InterpreterObject):
    def __init__(self, dep):
        InterpreterObject.__init__(self)
        self.held_object = dep
        self.methods.update({'found' : self.found_method})

    def found_method(self, args, kwargs):
        return True

class ExternalProgramHolder(InterpreterObject):
    def __init__(self, ep):
        InterpreterObject.__init__(self)
        self.held_object = ep
        self.methods.update({'found': self.found_method})

    def found_method(self, args, kwargs):
        return self.found()

    def found(self):
        return self.held_object.found()

    def get_command(self):
        return self.held_object.fullpath

    def get_name(self):
        return self.held_object.name

class ExternalLibraryHolder(InterpreterObject):
    def __init__(self, el):
        InterpreterObject.__init__(self)
        self.held_object = el
        self.methods.update({'found': self.found_method})

    def found(self):
        return self.held_object.found()

    def found_method(self, args, kwargs):
        return self.found()

    def get_filename(self):
        return self.held_object.fullpath

    def get_name(self):
        return self.held_object.name

    def get_compile_args(self):
        return self.held_object.get_compile_args()

    def get_link_args(self):
        return self.held_object.get_link_args()

    def get_exe_args(self):
        return self.held_object.get_exe_args()

class GeneratorHolder(InterpreterObject):
    def __init__(self, interpreter, args, kwargs):
        super().__init__()
        self.interpreter = interpreter
        self.held_object = build.Generator(args, kwargs)
        self.methods.update({'process' : self.process_method})

    def process_method(self, args, kwargs):
        check_stringlist(args)
        extras = mesonlib.stringlistify(kwargs.get('extra_args', []))
        gl = GeneratedListHolder(self, extras)
        [gl.add_file(os.path.join(self.interpreter.subdir, a)) for a in args]
        return gl

class GeneratedListHolder(InterpreterObject):
    def __init__(self, arg1, extra_args=[]):
        super().__init__()
        if isinstance(arg1, GeneratorHolder):
            self.held_object = build.GeneratedList(arg1.held_object, extra_args)
        else:
            self.held_object = arg1

    def add_file(self, a):
        self.held_object.add_file(a)

class BuildMachine(InterpreterObject):
    def __init__(self):
        InterpreterObject.__init__(self)
        self.methods.update({'system' : self.system_method,
                             'cpu_family' : self.cpu_family_method,
                             'cpu' : self.cpu_method,
                             'endian' : self.endian_method,
                            })

    # Python is inconsistent in its platform module.
    # It returns different values for the same cpu.
    # For x86 it might return 'x86', 'i686' or somesuch.
    # Do some canonicalization.
    def cpu_family_method(self, args, kwargs):
        trial = platform.machine().lower()
        if trial.startswith('i') and trial.endswith('86'):
            return 'x86'
        if trial.startswith('arm'):
            return 'arm'
        # Add fixes here as bugs are reported.
        return trial

    def cpu_method(self, args, kwargs):
        return platform.machine().lower()

    def system_method(self, args, kwargs):
        return platform.system().lower()

    def endian_method(self, args, kwargs):
        return sys.byteorder

# This class will provide both host_machine and
# target_machine
class CrossMachineInfo(InterpreterObject):
    def __init__(self, cross_info):
        InterpreterObject.__init__(self)
        minimum_cross_info = {'cpu', 'cpu_family', 'endian', 'system'}
        if set(cross_info) < minimum_cross_info:
            raise InterpreterException(
                'Machine info is currently {}\n'.format(cross_info) +
                'but is missing {}.'.format(minimum_cross_info - set(cross_info)))
        self.info = cross_info
        self.methods.update({'system' : self.system_method,
                             'cpu' : self.cpu_method,
                             'cpu_family' : self.cpu_family_method,
                             'endian' : self.endian_method,
                            })

    def system_method(self, args, kwargs):
        return self.info['system']

    def cpu_method(self, args, kwargs):
        return self.info['cpu']

    def cpu_family_method(self, args, kwargs):
        return self.info['cpu_family']

    def endian_method(self, args, kwargs):
        return self.info['endian']

class IncludeDirsHolder(InterpreterObject):
    def __init__(self, idobj):
        super().__init__()
        self.held_object = idobj

class Headers(InterpreterObject):

    def __init__(self, src_subdir, sources, kwargs):
        InterpreterObject.__init__(self)
        self.sources = sources
        self.source_subdir = src_subdir
        self.install_subdir = kwargs.get('subdir', '')
        self.custom_install_dir = kwargs.get('install_dir', None)
        if self.custom_install_dir is not None:
            if not isinstance(self.custom_install_dir, str):
                raise InterpreterException('Custom_install_dir must be a string.')

    def set_install_subdir(self, subdir):
        self.install_subdir = subdir

    def get_install_subdir(self):
        return self.install_subdir

    def get_source_subdir(self):
        return self.source_subdir

    def get_sources(self):
        return self.sources

    def get_custom_install_dir(self):
        return self.custom_install_dir

class DataHolder(InterpreterObject):
    def __init__(self, in_sourcetree, source_subdir, sources, kwargs):
        super().__init__()
        kwsource = mesonlib.stringlistify(kwargs.get('sources', []))
        sources += kwsource
        check_stringlist(sources)
        install_dir = kwargs.get('install_dir', None)
        if not isinstance(install_dir, str):
            raise InterpreterException('Custom_install_dir must be a string.')
        self.held_object = build.Data(in_sourcetree, source_subdir, sources, install_dir)

    def get_source_subdir(self):
        return self.held_object.source_subdir

    def get_sources(self):
        return self.held_object.sources

    def get_install_dir(self):
        return self.held_object.install_dir

class InstallDir(InterpreterObject):
    def __init__(self, source_subdir, installable_subdir, install_dir):
        InterpreterObject.__init__(self)
        self.source_subdir = source_subdir
        self.installable_subdir = installable_subdir
        self.install_dir = install_dir

class Man(InterpreterObject):

    def __init__(self, source_subdir, sources, kwargs):
        InterpreterObject.__init__(self)
        self.source_subdir = source_subdir
        self.sources = sources
        self.validate_sources()
        if len(kwargs) > 1:
            raise InvalidArguments('Man function takes at most one keyword arguments.')
        self.custom_install_dir = kwargs.get('install_dir', None)
        if self.custom_install_dir is not None and not isinstance(self.custom_install_dir, str):
            raise InterpreterException('Custom_install_dir must be a string.')

    def validate_sources(self):
        for s in self.sources:
            num = int(s.split('.')[-1])
            if num < 1 or num > 8:
                raise InvalidArguments('Man file must have a file extension of a number between 1 and 8')

    def get_custom_install_dir(self):
        return self.custom_install_dir

    def get_sources(self):
        return self.sources

    def get_source_subdir(self):
        return self.source_subdir

class GeneratedObjectsHolder(InterpreterObject):
    def __init__(self, held_object):
        super().__init__()
        self.held_object = held_object

class BuildTargetHolder(InterpreterObject):
    def __init__(self, target, interp):
        super().__init__()
        self.held_object = target
        self.interpreter = interp
        self.methods.update({'extract_objects' : self.extract_objects_method,
                             'extract_all_objects' : self.extract_all_objects_method,
                             'get_id': self.get_id_method,
                             'outdir' : self.outdir_method,
                             'private_dir_include' : self.private_dir_include_method,
                             })

    def is_cross(self):
        return self.held_object.is_cross()

    def private_dir_include_method(self, args, kwargs):
        return IncludeDirsHolder(build.IncludeDirs('', [],
                    [self.interpreter.backend.get_target_private_dir(self.held_object)]))

    def outdir_method(self, args, kwargs):
        return self.interpreter.backend.get_target_dir(self.held_object)

    def extract_objects_method(self, args, kwargs):
        gobjs = self.held_object.extract_objects(args)
        return GeneratedObjectsHolder(gobjs)

    def extract_all_objects_method(self, args, kwargs):
        gobjs = self.held_object.extract_all_objects()
        return GeneratedObjectsHolder(gobjs)

    def get_id_method(self, args, kwargs):
        return self.held_object.get_id()

class ExecutableHolder(BuildTargetHolder):
    def __init__(self, target, interp):
        super().__init__(target, interp)

class StaticLibraryHolder(BuildTargetHolder):
    def __init__(self, target, interp):
        super().__init__(target, interp)

class SharedLibraryHolder(BuildTargetHolder):
    def __init__(self, target, interp):
        super().__init__(target, interp)

class JarHolder(BuildTargetHolder):
    def __init__(self, target, interp):
        super().__init__(target, interp)

class CustomTargetHolder(InterpreterObject):
    def __init__(self, object_to_hold):
        self.held_object = object_to_hold

    def is_cross(self):
        return self.held_object.is_cross()

    def extract_objects_method(self, args, kwargs):
        gobjs = self.held_object.extract_objects(args)
        return GeneratedObjectsHolder(gobjs)

class RunTargetHolder(InterpreterObject):
    def __init__(self, name, command, args, subdir):
        self.held_object = build.RunTarget(name, command, args, subdir)

class Test(InterpreterObject):
    def __init__(self, name, suite, exe, is_parallel, cmd_args, env, should_fail, valgrind_args, timeout, workdir):
        InterpreterObject.__init__(self)
        self.name = name
        self.suite = suite
        self.exe = exe
        self.is_parallel = is_parallel
        self.cmd_args = cmd_args
        self.env = env
        self.should_fail = should_fail
        self.valgrind_args = valgrind_args
        self.timeout = timeout
        self.workdir = workdir

    def get_exe(self):
        return self.exe

    def get_name(self):
        return self.name

class SubprojectHolder(InterpreterObject):

    def __init__(self, subinterpreter):
        super().__init__()
        self.subinterpreter = subinterpreter
        self.methods.update({'get_variable' : self.get_variable_method,
                            })

    def get_variable_method(self, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('Get_variable takes one argument.')
        varname = args[0]
        if not isinstance(varname, str):
            raise InterpreterException('Get_variable takes a string argument.')
        return self.subinterpreter.variables[varname]

class CompilerHolder(InterpreterObject):
    def __init__(self, compiler, env):
        InterpreterObject.__init__(self)
        self.compiler = compiler
        self.environment = env
        self.methods.update({'compiles': self.compiles_method,
                             'links': self.links_method,
                             'get_id': self.get_id_method,
                             'sizeof': self.sizeof_method,
                             'has_header': self.has_header_method,
                             'run' : self.run_method,
                             'has_function' : self.has_function_method,
                             'has_member' : self.has_member_method,
                             'has_type' : self.has_type_method,
                             'alignment' : self.alignment_method,
                             'version' : self.version_method,
                             'cmd_array' : self.cmd_array_method,
                            })

    def version_method(self, args, kwargs):
        return self.compiler.version

    def cmd_array_method(self, args, kwargs):
        return self.compiler.exelist

    def determine_args(self, kwargs):
        nobuiltins = kwargs.get('no_builtin_args', False)
        if not isinstance(nobuiltins, bool):
            raise InterpreterException('Type of no_builtin_args not a boolean.')
        args = []
        if not nobuiltins:
            opts = self.environment.coredata.compiler_options
            args += self.compiler.get_option_compile_args(opts)
            args += self.compiler.get_option_link_args(opts)
        args += mesonlib.stringlistify(kwargs.get('args', []))
        return args

    def alignment_method(self, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('Alignment method takes exactly one positional argument.')
        check_stringlist(args)
        typename = args[0]
        extra_args = mesonlib.stringlistify(kwargs.get('args', []))
        result = self.compiler.alignment(typename, self.environment, extra_args)
        mlog.log('Checking for alignment of "', mlog.bold(typename), '": ', result, sep='')
        return result

    def run_method(self, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('Run method takes exactly one positional argument.')
        check_stringlist(args)
        code = args[0]
        testname = kwargs.get('name', '')
        if not isinstance(testname, str):
            raise InterpreterException('Testname argument must be a string.')
        extra_args = self.determine_args(kwargs)
        result = self.compiler.run(code, extra_args)
        if len(testname) > 0:
            if not result.compiled:
                h = mlog.red('DID NOT COMPILE')
            elif result.returncode == 0:
                h = mlog.green('YES')
            else:
                h = mlog.red('NO (%d)' % result.returncode)
            mlog.log('Checking if "', mlog.bold(testname), '" runs : ', h, sep='')
        return TryRunResultHolder(result)

    def get_id_method(self, args, kwargs):
        return self.compiler.get_id()

    def has_member_method(self, args, kwargs):
        if len(args) != 2:
            raise InterpreterException('Has_member takes exactly two arguments.')
        check_stringlist(args)
        typename = args[0]
        membername = args[1]
        prefix = kwargs.get('prefix', '')
        if not isinstance(prefix, str):
            raise InterpreterException('Prefix argument of has_function must be a string.')
        extra_args = self.determine_args(kwargs)
        had = self.compiler.has_member(typename, membername, prefix, extra_args)
        if had:
            hadtxt = mlog.green('YES')
        else:
            hadtxt = mlog.red('NO')
        mlog.log('Checking whether type "', mlog.bold(typename),
                 '" has member "', mlog.bold(membername), '": ', hadtxt, sep='')
        return had

    def has_function_method(self, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('Has_function takes exactly one argument.')
        check_stringlist(args)
        funcname = args[0]
        prefix = kwargs.get('prefix', '')
        if not isinstance(prefix, str):
            raise InterpreterException('Prefix argument of has_function must be a string.')
        extra_args = self.determine_args(kwargs)
        had = self.compiler.has_function(funcname, prefix, self.environment, extra_args)
        if had:
            hadtxt = mlog.green('YES')
        else:
            hadtxt = mlog.red('NO')
        mlog.log('Checking for function "', mlog.bold(funcname), '": ', hadtxt, sep='')
        return had

    def has_type_method(self, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('Has_type takes exactly one argument.')
        check_stringlist(args)
        typename = args[0]
        prefix = kwargs.get('prefix', '')
        if not isinstance(prefix, str):
            raise InterpreterException('Prefix argument of has_type must be a string.')
        extra_args = self.determine_args(kwargs)
        had = self.compiler.has_type(typename, prefix, extra_args)
        if had:
            hadtxt = mlog.green('YES')
        else:
            hadtxt = mlog.red('NO')
        mlog.log('Checking for type "', mlog.bold(typename), '": ', hadtxt, sep='')
        return had

    def sizeof_method(self, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('Sizeof takes exactly one argument.')
        check_stringlist(args)
        element = args[0]
        prefix = kwargs.get('prefix', '')
        if not isinstance(prefix, str):
            raise InterpreterException('Prefix argument of sizeof must be a string.')
        extra_args = self.determine_args(kwargs)
        esize = self.compiler.sizeof(element, prefix, self.environment, extra_args)
        mlog.log('Checking for size of "%s": %d' % (element, esize))
        return esize

    def compiles_method(self, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('compiles method takes exactly one argument.')
        check_stringlist(args)
        code = args[0]
        testname = kwargs.get('name', '')
        if not isinstance(testname, str):
            raise InterpreterException('Testname argument must be a string.')
        extra_args = self.determine_args(kwargs)
        result = self.compiler.compiles(code, extra_args)
        if len(testname) > 0:
            if result:
                h = mlog.green('YES')
            else:
                h = mlog.red('NO')
            mlog.log('Checking if "', mlog.bold(testname), '" compiles : ', h, sep='')
        return result

    def links_method(self, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('links method takes exactly one argument.')
        check_stringlist(args)
        code = args[0]
        testname = kwargs.get('name', '')
        if not isinstance(testname, str):
            raise InterpreterException('Testname argument must be a string.')
        extra_args = self.determine_args(kwargs)
        result = self.compiler.links(code, extra_args)
        if len(testname) > 0:
            if result:
                h = mlog.green('YES')
            else:
                h = mlog.red('NO')
            mlog.log('Checking if "', mlog.bold(testname), '" links : ', h, sep='')
        return result

    def has_header_method(self, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('has_header method takes exactly one argument.')
        check_stringlist(args)
        string = args[0]
        extra_args = self.determine_args(kwargs)
        haz = self.compiler.has_header(string, extra_args)
        if haz:
            h = mlog.green('YES')
        else:
            h = mlog.red('NO')
        mlog.log('Has header "%s":' % string, h)
        return haz

class ModuleState:
    pass

class ModuleHolder(InterpreterObject):
    def __init__(self, modname, module, interpreter):
        InterpreterObject.__init__(self)
        self.modname = modname
        self.held_object = module
        self.interpreter = interpreter

    def method_call(self, method_name, args, kwargs):
        try:
            fn = getattr(self.held_object, method_name)
        except AttributeError:
            raise InvalidArguments('Module %s does not have method %s.' % (self.modname, method_name))
        state = ModuleState()
        state.build_to_src = os.path.relpath(self.interpreter.environment.get_source_dir(),
                                             self.interpreter.environment.get_build_dir())
        state.subdir = self.interpreter.subdir
        state.environment = self.interpreter.environment
        state.project_name = self.interpreter.build.project_name
        state.project_version = self.interpreter.build.dep_manifest[self.interpreter.active_projectname]
        state.compilers = self.interpreter.build.compilers
        state.targets = self.interpreter.build.targets
        state.headers = self.interpreter.build.get_headers()
        state.man = self.interpreter.build.get_man()
        state.global_args = self.interpreter.build.global_args
        value = fn(state, args, kwargs)
        return self.interpreter.module_method_callback(value)

class MesonMain(InterpreterObject):
    def __init__(self, build, interpreter):
        InterpreterObject.__init__(self)
        self.build = build
        self.interpreter = interpreter
        self.methods.update({'get_compiler': self.get_compiler_method,
                             'is_cross_build' : self.is_cross_build_method,
                             'has_exe_wrapper' : self.has_exe_wrapper_method,
                             'is_unity' : self.is_unity_method,
                             'is_subproject' : self.is_subproject_method,
                             'current_source_dir' : self.current_source_dir_method,
                             'current_build_dir' : self.current_build_dir_method,
                             'source_root' : self.source_root_method,
                             'build_root' : self.build_root_method,
                             'add_install_script' : self.add_install_script_method,
                             'install_dependency_manifest': self.install_dependency_manifest_method,
                             'project_version': self.project_version_method,
                            })

    def add_install_script_method(self, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('Set_install_script takes exactly one argument.')
        check_stringlist(args)
        scriptbase = args[0]
        scriptfile = os.path.join(self.interpreter.environment.source_dir,
                                  self.interpreter.subdir, scriptbase)
        if not os.path.isfile(scriptfile):
            raise InterpreterException('Can not find install script %s.' % scriptbase)
        self.build.install_scripts.append(build.InstallScript([scriptfile]))

    def current_source_dir_method(self, args, kwargs):
        src = self.interpreter.environment.source_dir
        sub = self.interpreter.subdir
        if sub == '':
            return src
        return os.path.join(src, sub)

    def current_build_dir_method(self, args, kwargs):
        src = self.interpreter.environment.build_dir
        sub = self.interpreter.subdir
        if sub == '':
            return src
        return os.path.join(src, sub)

    def source_root_method(self, args, kwargs):
        return self.interpreter.environment.source_dir

    def build_root_method(self, args, kwargs):
        return self.interpreter.environment.build_dir

    def has_exe_wrapper_method(self, args, kwargs):
        if self.is_cross_build_method(None, None) and 'binaries' in self.build.environment.cross_info.config:
            return 'exe_wrap' in self.build.environment.cross_info.config['binaries']
        return True  # This is semantically confusing.

    def is_cross_build_method(self, args, kwargs):
        return self.build.environment.is_cross_build()

    def get_compiler_method(self, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('get_compiler_method must have one and only one argument.')
        cname = args[0]
        native = kwargs.get('native', None)
        if native is None:
            if self.build.environment.is_cross_build():
                native = False
            else:
                native = True
        if not isinstance(native, bool):
            raise InterpreterException('Type of "native" must be a boolean.')
        if native:
            clist = self.build.compilers
        else:
            clist = self.build.cross_compilers
        for c in clist:
            if c.get_language() == cname:
                return CompilerHolder(c, self.build.environment)
        raise InterpreterException('Tried to access compiler for unspecified language "%s".' % cname)

    def is_unity_method(self, args, kwargs):
        return self.build.environment.coredata.get_builtin_option('unity')

    def is_subproject_method(self, args, kwargs):
        return self.interpreter.is_subproject()

    def install_dependency_manifest_method(self, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('Must specify manifest install file name')
        if not isinstance(args[0], str):
            raise InterpreterException('Argument must be a string.')
        self.build.dep_manifest_name = args[0]

    def project_version_method(self, args, kwargs):
        return self.build.dep_manifest[self.interpreter.active_projectname]['version']

class Interpreter():

    def __init__(self, build, backend, subproject='', subdir='', subproject_dir='subprojects'):
        self.build = build
        self.backend = backend
        self.subproject = subproject
        self.subdir = subdir
        self.source_root = build.environment.get_source_dir()
        self.subproject_dir = subproject_dir
        option_file = os.path.join(self.source_root, self.subdir, 'meson_options.txt')
        if os.path.exists(option_file):
            oi = optinterpreter.OptionInterpreter(self.subproject, \
                                                  self.build.environment.cmd_line_options.projectoptions)
            oi.process(option_file)
            self.build.environment.merge_options(oi.options)
        mesonfile = os.path.join(self.source_root, self.subdir, environment.build_filename)
        if not os.path.isfile(mesonfile):
            raise InvalidArguments('Missing Meson file in %s' % mesonfile)
        code = open(mesonfile).read()
        if len(code.strip()) == 0:
            raise InvalidCode('Builder file is empty.')
        assert(isinstance(code, str))
        try:
            self.ast = mparser.Parser(code).parse()
        except coredata.MesonException as me:
            me.file = environment.build_filename
            raise me
        self.sanity_check_ast()
        self.variables = {}
        self.builtin = {}
        self.builtin['build_machine'] = BuildMachine()
        if not self.build.environment.is_cross_build():
            self.builtin['host_machine'] = self.builtin['build_machine']
            self.builtin['target_machine'] = self.builtin['build_machine']
        else:
            cross_info = self.build.environment.cross_info
            if cross_info.has_host():
                self.builtin['host_machine'] = CrossMachineInfo(cross_info.config['host_machine'])
            else:
                self.builtin['host_machine'] = self.builtin['build_machine']
            if cross_info.has_target():
                self.builtin['target_machine'] = CrossMachineInfo(cross_info.config['target_machine'])
            else:
                self.builtin['target_machine'] = self.builtin['host_machine']
        self.builtin['meson'] = MesonMain(build, self)
        self.environment = build.environment
        self.build_func_dict()
        self.build_def_files = [os.path.join(self.subdir, environment.build_filename)]
        self.coredata = self.environment.get_coredata()
        self.generators = []
        self.visited_subdirs = {}
        self.global_args_frozen = False
        self.subprojects = {}
        self.subproject_stack = []

    def build_func_dict(self):
        self.funcs = {'project' : self.func_project,
                      'message' : self.func_message,
                      'error' : self.func_error,
                      'executable': self.func_executable,
                      'dependency' : self.func_dependency,
                      'static_library' : self.func_static_lib,
                      'shared_library' : self.func_shared_lib,
                      'library' : self.func_library,
                      'jar' : self.func_jar,
                      'build_target': self.func_build_target,
                      'custom_target' : self.func_custom_target,
                      'run_target' : self.func_run_target,
                      'generator' : self.func_generator,
                      'test' : self.func_test,
                      'benchmark' : self.func_benchmark,
                      'install_headers' : self.func_install_headers,
                      'install_man' : self.func_install_man,
                      'subdir' : self.func_subdir,
                      'install_data' : self.func_install_data,
                      'install_subdir' : self.func_install_subdir,
                      'configure_file' : self.func_configure_file,
                      'include_directories' : self.func_include_directories,
                      'add_global_arguments' : self.func_add_global_arguments,
                      'add_languages' : self.func_add_languages,
                      'find_program' : self.func_find_program,
                      'find_library' : self.func_find_library,
                      'configuration_data' : self.func_configuration_data,
                      'run_command' : self.func_run_command,
                      'gettext' : self.func_gettext,
                      'option' : self.func_option,
                      'get_option' : self.func_get_option,
                      'subproject' : self.func_subproject,
                      'vcs_tag' : self.func_vcs_tag,
                      'set_variable' : self.func_set_variable,
                      'is_variable' : self.func_is_variable,
                      'get_variable' : self.func_get_variable,
                      'import' : self.func_import,
                      'files' : self.func_files,
                      'declare_dependency': self.func_declare_dependency,
                      'assert': self.func_assert,
                     }

    def module_method_callback(self, invalues):
        unwrap_single = False
        if invalues is None:
            return
        if not isinstance(invalues, list):
            unwrap_single = True
            invalues = [invalues]
        outvalues = []
        for v in invalues:
            if isinstance(v, build.CustomTarget):
                if v.name in self.build.targets:
                    raise InterpreterException('Tried to create target %s which already exists.' % v.name)
                self.build.targets[v.name] = v
                outvalues.append(CustomTargetHolder(v))
            elif isinstance(v, int) or isinstance(v, str):
                outvalues.append(v)
            elif isinstance(v, build.Executable):
                if v.name in self.build.targets:
                    raise InterpreterException('Tried to create target %s which already exists.' % v.name)
                self.build.targets[v.name] = v
                outvalues.append(ExecutableHolder(v))
            elif isinstance(v, list):
                outvalues.append(self.module_method_callback(v))
            elif isinstance(v, build.GeneratedList):
                outvalues.append(GeneratedListHolder(v))
            elif isinstance(v, build.RunTarget):
                if v.name in self.build.targets:
                    raise InterpreterException('Tried to create target %s which already exists.' % v.name)
                self.build.targets[v.name] = v
            elif isinstance(v, build.InstallScript):
                self.build.install_scripts.append(v)
            elif isinstance(v, build.Data):
                self.build.data.append(v)
            else:
                print(v)
                raise InterpreterException('Module returned a value of unknown type.')
        if len(outvalues) == 1 and unwrap_single:
            return outvalues[0]
        return outvalues

    def get_build_def_files(self):
        return self.build_def_files

    def get_variables(self):
        return self.variables

    def sanity_check_ast(self):
        if not isinstance(self.ast, mparser.CodeBlockNode):
            raise InvalidCode('AST is of invalid type. Possibly a bug in the parser.')
        if len(self.ast.lines) == 0:
            raise InvalidCode('No statements in code.')
        first = self.ast.lines[0]
        if not isinstance(first, mparser.FunctionNode) or first.func_name != 'project':
            raise InvalidCode('First statement must be a call to project')

    def run(self):
        self.evaluate_codeblock(self.ast)
        mlog.log('Build targets in project:', mlog.bold(str(len(self.build.targets))))

    def evaluate_codeblock(self, node):
        if node is None:
            return
        if not isinstance(node, mparser.CodeBlockNode):
            e = InvalidCode('Tried to execute a non-codeblock. Possibly a bug in the parser.')
            e.lineno = node.lineno
            e.colno = node.colno
            raise e
        statements = node.lines
        i = 0
        while i < len(statements):
            cur = statements[i]
            try:
                self.evaluate_statement(cur)
            except Exception as e:
                if not(hasattr(e, 'lineno')):
                    e.lineno = cur.lineno
                    e.colno = cur.colno
                    e.file = os.path.join(self.subdir, 'meson.build')
                raise e
            i += 1 # In THE FUTURE jump over blocks and stuff.

    def get_variable(self, varname):
        if varname in self.builtin:
            return self.builtin[varname]
        if varname in self.variables:
            return self.variables[varname]
        raise InvalidCode('Unknown variable "%s".' % varname)

    def func_set_variable(self, node, args, kwargs):
        if len(args) != 2:
            raise InvalidCode('Set_variable takes two arguments.')
        varname = args[0]
        value = self.to_native(args[1])
        self.set_variable(varname, value)

    @noKwargs
    def func_get_variable(self, node, args, kwargs):
        if len(args)<1 or len(args)>2:
            raise InvalidCode('Get_variable takes one or two arguments.')
        varname = args[0]
        if not isinstance(varname, str):
            raise InterpreterException('First argument must be a string.')
        try:
            return self.variables[varname]
        except KeyError:
            pass
        if len(args) == 2:
            return args[1]
        raise InterpreterException('Tried to get unknown variable "%s".' % varname)

    @stringArgs
    @noKwargs
    def func_is_variable(self, node, args, kwargs):
        if len(args) != 1:
            raise InvalidCode('Is_variable takes two arguments.')
        varname = args[0]
        return varname in self.variables

    @stringArgs
    @noKwargs
    def func_import(self, node, args, kwargs):
        if len(args) != 1:
            raise InvalidCode('Import takes one argument.')
        modname = args[0]
        if not modname in self.environment.coredata.modules:
            module = importlib.import_module('modules.' + modname).initialize()
            self.environment.coredata.modules[modname] = module
        return ModuleHolder(modname, self.environment.coredata.modules[modname], self)

    @stringArgs
    @noKwargs
    def func_files(self, node, args, kwargs):
        return [mesonlib.File.from_source_file(self.environment.source_dir, self.subdir, fname) for fname in args]

    @noPosargs
    def func_declare_dependency(self, node, args, kwargs):
        incs = kwargs.get('include_directories', [])
        if not isinstance(incs, list):
            incs = [incs]
        libs = kwargs.get('link_with', [])
        if not isinstance(libs, list):
            libs = [libs]
        sources = kwargs.get('sources', [])
        if not isinstance(sources, list):
            sources = [sources]
        sources = self.source_strings_to_files(self.flatten(sources))
        deps = kwargs.get('dependencies', [])
        if not isinstance(deps, list):
            deps = [deps]
        final_deps = []
        for d in deps:
            try:
                d = d.held_object
            except Exception:
                pass
            if not isinstance(d, (dependencies.Dependency, dependencies.ExternalLibrary)):
                raise InterpreterException('Dependencies must be external deps')
            final_deps.append(d)
        dep = dependencies.InternalDependency(incs, libs, sources, final_deps)
        return InternalDependencyHolder(dep)

    @noKwargs
    def func_assert(self, node, args, kwargs):
        if len(args) != 2:
            raise InterpreterException('Assert takes exactly two arguments')
        value, message = args
        if not isinstance(value, bool):
            raise InterpreterException('Assert value not bool.')
        if not isinstance(message, str):
            raise InterpreterException('Assert message not a string.')
        if not value:
            raise InterpreterException('Assert failed: ' + message)

    def set_variable(self, varname, variable):
        if variable is None:
            raise InvalidCode('Can not assign None to variable.')
        if not isinstance(varname, str):
            raise InvalidCode('First argument to set_variable must be a string.')
        if not self.is_assignable(variable):
            raise InvalidCode('Assigned value not of assignable type.')
        if re.match('[_a-zA-Z][_0-9a-zA-Z]*$', varname) is None:
            raise InvalidCode('Invalid variable name: ' + varname)
        if varname in self.builtin:
            raise InvalidCode('Tried to overwrite internal variable "%s"' % varname)
        self.variables[varname] = variable

    def evaluate_statement(self, cur):
        if isinstance(cur, mparser.FunctionNode):
            return self.function_call(cur)
        elif isinstance(cur, mparser.AssignmentNode):
            return self.assignment(cur)
        elif isinstance(cur, mparser.MethodNode):
            return self.method_call(cur)
        elif isinstance(cur, mparser.StringNode):
            return cur.value
        elif isinstance(cur, mparser.BooleanNode):
            return cur.value
        elif isinstance(cur, mparser.IfClauseNode):
            return self.evaluate_if(cur)
        elif isinstance(cur, mparser.IdNode):
            return self.get_variable(cur.value)
        elif isinstance(cur, mparser.ComparisonNode):
            return self.evaluate_comparison(cur)
        elif isinstance(cur, mparser.ArrayNode):
            return self.evaluate_arraystatement(cur)
        elif isinstance(cur, mparser.NumberNode):
            return cur.value
        elif isinstance(cur, mparser.AndNode):
            return self.evaluate_andstatement(cur)
        elif isinstance(cur, mparser.OrNode):
            return self.evaluate_orstatement(cur)
        elif isinstance(cur, mparser.NotNode):
            return self.evaluate_notstatement(cur)
        elif isinstance(cur, mparser.UMinusNode):
            return self.evaluate_uminusstatement(cur)
        elif isinstance(cur, mparser.ArithmeticNode):
            return self.evaluate_arithmeticstatement(cur)
        elif isinstance(cur, mparser.ForeachClauseNode):
            return self.evaluate_foreach(cur)
        elif isinstance(cur, mparser.PlusAssignmentNode):
            return self.evaluate_plusassign(cur)
        elif isinstance(cur, mparser.IndexNode):
            return self.evaluate_indexing(cur)
        elif self.is_elementary_type(cur):
            return cur
        else:
            raise InvalidCode("Unknown statement.")

    def validate_arguments(self, args, argcount, arg_types):
        if argcount is not None:
            if argcount != len(args):
                raise InvalidArguments('Expected %d arguments, got %d.' %
                                       (argcount, len(args)))
        for i in range(min(len(args), len(arg_types))):
            wanted = arg_types[i]
            actual = args[i]
            if wanted != None:
                if not isinstance(actual, wanted):
                    raise InvalidArguments('Incorrect argument type.')

    def func_run_command(self, node, args, kwargs):
        if len(args) < 1:
            raise InterpreterException('Not enough arguments')
        cmd = args[0]
        cargs = args[1:]
        if isinstance(cmd, ExternalProgramHolder):
            cmd = cmd.get_command()
        elif isinstance(cmd, str):
            cmd = [cmd]
        else:
            raise InterpreterException('First argument is of incorrect type.')
        check_stringlist(cargs, 'Run_command arguments must be strings.')
        args = cmd + cargs
        in_builddir = kwargs.get('in_builddir', False)
        if not isinstance(in_builddir, bool):
            raise InterpreterException('in_builddir must be boolean.')
        return RunProcess(args, self.environment.source_dir, self.environment.build_dir,
                          self.subdir, in_builddir)

    @stringArgs
    def func_gettext(self, nodes, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('Gettext requires one positional argument (package name).')
        packagename = args[0]
        languages = kwargs.get('languages', None)
        check_stringlist(languages, 'Argument languages must be a list of strings.')
        # TODO: check that elements are strings
        if len(self.build.pot) > 0:
            raise InterpreterException('More than one gettext definition currently not supported.')
        self.build.pot.append((packagename, languages, self.subdir))

    def func_option(self, nodes, args, kwargs):
        raise InterpreterException('Tried to call option() in build description file. All options must be in the option file.')

    @stringArgs
    def func_subproject(self, nodes, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('Subproject takes exactly one argument')
        dirname = args[0]
        return self.do_subproject(dirname, kwargs)

    def do_subproject(self, dirname, kwargs):
        if self.subdir != '':
            segs = os.path.split(self.subdir)
            if len(segs) != 2 or segs[0] != self.subproject_dir:
                raise InterpreterException('Subprojects must be defined at the root directory.')
        if dirname in self.subproject_stack:
            fullstack = self.subproject_stack + [dirname]
            incpath = ' => '.join(fullstack)
            raise InterpreterException('Recursive include of subprojects: %s.' % incpath)
        if dirname in self.subprojects:
            return self.subprojects[dirname]
        r = wrap.Resolver(os.path.join(self.build.environment.get_source_dir(), self.subproject_dir))
        resolved = r.resolve(dirname)
        if resolved is None:
            raise InterpreterException('Subproject directory does not exist and can not be downloaded.')
        subdir = os.path.join(self.subproject_dir, resolved)
        os.makedirs(os.path.join(self.build.environment.get_build_dir(), subdir), exist_ok=True)
        self.global_args_frozen = True
        mlog.log('\nExecuting subproject ', mlog.bold(dirname), '.\n', sep='')
        subi = Interpreter(self.build, self.backend, dirname, subdir, self.subproject_dir)
        subi.subprojects = self.subprojects

        subi.subproject_stack = self.subproject_stack + [dirname]
        current_active = self.active_projectname
        subi.run()
        if 'version' in kwargs:
            pv = subi.project_version
            wanted = kwargs['version']
            if not mesonlib.version_compare(pv, wanted):
                raise InterpreterException('Subproject %s version is %s but %s required.' % (dirname, pv, wanted))
        self.active_projectname = current_active
        mlog.log('\nSubproject', mlog.bold(dirname), 'finished.')
        self.build.subprojects[dirname] = True
        self.subprojects.update(subi.subprojects)
        self.subprojects[dirname] = SubprojectHolder(subi)
        self.build_def_files += subi.build_def_files
        return self.subprojects[dirname]

    @stringArgs
    @noKwargs
    def func_get_option(self, nodes, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('Argument required for get_option.')
        optname = args[0]
        try:
            return self.environment.get_coredata().get_builtin_option(optname)
        except RuntimeError:
            pass
        try:
            return self.environment.coredata.compiler_options[optname].value
        except KeyError:
            pass
        if optname not in coredata.builtin_options and self.is_subproject():
            optname = self.subproject + ':' + optname
        try:
            return self.environment.coredata.user_options[optname].value
        except KeyError:
            raise InterpreterException('Tried to access unknown option "%s".' % optname)

    @noKwargs
    def func_configuration_data(self, node, args, kwargs):
        if len(args) != 0:
            raise InterpreterException('configuration_data takes no arguments')
        return ConfigurationDataHolder()

    def parse_default_options(self, default_options):
        if not isinstance(default_options, list):
            default_options = [default_options]
        for option in default_options:
            if not isinstance(option, str):
                mlog.debug(option)
                raise InterpreterException('Default options must be strings')
            if '=' not in option:
                raise InterpreterException('All default options must be of type key=value.')
            key, value = option.split('=', 1)
            builtin_options = self.coredata.builtin_options
            if key in builtin_options:
                if not hasattr(self.environment.cmd_line_options, value):
                    self.coredata.set_builtin_option(key, value)
                # If this was set on the command line, do not override.
            else:
                newoptions = [option] + self.environment.cmd_line_options.projectoptions
                self.environment.cmd_line_options.projectoptions = newoptions

    @stringArgs
    def func_project(self, node, args, kwargs):
        if len(args) < 2:
            raise InvalidArguments('Not enough arguments to project(). Needs at least the project name and one language')

        if not self.is_subproject():
            self.build.project_name = args[0]
            if self.environment.first_invocation and 'default_options' in kwargs:
                self.parse_default_options(kwargs['default_options'])
        self.active_projectname = args[0]
        self.project_version = kwargs.get('version', 'undefined')
        proj_license = mesonlib.stringlistify(kwargs.get('license', 'unknown'))
        self.build.dep_manifest[args[0]] = {'version': self.project_version,
                                            'license': proj_license}
        if self.subproject in self.build.projects:
            raise InvalidCode('Second call to project().')
        if not self.is_subproject() and 'subproject_dir' in kwargs:
            self.subproject_dir = kwargs['subproject_dir']

        if 'meson_version' in kwargs:
            cv = coredata.version
            pv = kwargs['meson_version']
            if not mesonlib.version_compare(cv, pv):
                raise InterpreterException('Meson version is %s but project requires %s.' % (cv, pv))
        self.build.projects[self.subproject] = args[0]
        mlog.log('Project name: ', mlog.bold(args[0]), sep='')
        self.add_languages(node, args[1:])
        langs = self.coredata.compilers.keys()
        if 'vala' in langs:
            if not 'c' in langs:
                raise InterpreterException('Compiling Vala requires C. Add C to your project languages and rerun Meson.')

    @noKwargs
    @stringArgs
    def func_add_languages(self, node, args, kwargs):
        self.add_languages(node, args)

    @noKwargs
    def func_message(self, node, args, kwargs):
        # reduce arguments again to avoid flattening posargs
        (posargs, _) = self.reduce_arguments(node.args)
        if len(posargs) != 1:
            raise InvalidArguments('Expected 1 argument, got %d' % len(posargs))

        arg = posargs[0]
        if isinstance(arg, list):
            argstr = stringifyUserArguments(arg)
        elif isinstance(arg, str):
            argstr = arg
        elif isinstance(arg, int):
            argstr = str(arg)
        else:
            raise InvalidArguments('Function accepts only strings, integers, lists and lists thereof.')

        mlog.log(mlog.bold('Message:'), argstr)
        return


    @noKwargs
    def func_error(self, node, args, kwargs):
        self.validate_arguments(args, 1, [str])
        raise InterpreterException('Error encountered: ' + args[0])

    def add_languages(self, node, args):
        need_cross_compiler = self.environment.is_cross_build() and self.environment.cross_info.need_cross_compiler()
        for lang in args:
            lang = lang.lower()
            if lang in self.coredata.compilers:
                comp = self.coredata.compilers[lang]
                cross_comp = self.coredata.cross_compilers.get(lang, None)
            else:
                cross_comp = None
                if lang == 'c':
                    comp = self.environment.detect_c_compiler(False)
                    if need_cross_compiler:
                        cross_comp = self.environment.detect_c_compiler(True)
                elif lang == 'cpp':
                    comp = self.environment.detect_cpp_compiler(False)
                    if need_cross_compiler:
                        cross_comp = self.environment.detect_cpp_compiler(True)
                elif lang == 'objc':
                    comp = self.environment.detect_objc_compiler(False)
                    if need_cross_compiler:
                        cross_comp = self.environment.detect_objc_compiler(True)
                elif lang == 'objcpp':
                    comp = self.environment.detect_objcpp_compiler(False)
                    if need_cross_compiler:
                        cross_comp = self.environment.detect_objcpp_compiler(True)
                elif lang == 'java':
                    comp = self.environment.detect_java_compiler()
                    if need_cross_compiler:
                        cross_comp = comp # Java is platform independent.
                elif lang == 'cs':
                    comp = self.environment.detect_cs_compiler()
                    if need_cross_compiler:
                        cross_comp = comp # C# is platform independent.
                elif lang == 'vala':
                    comp = self.environment.detect_vala_compiler()
                    if need_cross_compiler:
                        cross_comp = comp # Vala is too (I think).
                elif lang == 'rust':
                    comp = self.environment.detect_rust_compiler()
                    if need_cross_compiler:
                        cross_comp = comp # FIXME, probably not correct.
                elif lang == 'fortran':
                    comp = self.environment.detect_fortran_compiler(False)
                    if need_cross_compiler:
                        cross_comp = self.environment.detect_fortran_compiler(True)
                elif lang == 'swift':
                    comp = self.environment.detect_swift_compiler()
                    if need_cross_compiler:
                        raise InterpreterException('Cross compilation with Swift is not working yet.')
                        #cross_comp = self.environment.detect_fortran_compiler(True)
                else:
                    raise InvalidCode('Tried to use unknown language "%s".' % lang)
                comp.sanity_check(self.environment.get_scratch_dir())
                self.coredata.compilers[lang] = comp
                if cross_comp is not None:
                    cross_comp.sanity_check(self.environment.get_scratch_dir())
                    self.coredata.cross_compilers[lang] = cross_comp
                new_options = comp.get_options()
                optprefix = lang + '_'
                for i in new_options:
                    if not i.startswith(optprefix):
                        raise InterpreterException('Internal error, %s has incorrect prefix.' % i)
                    cmd_prefix = i + '='
                    for cmd_arg in self.environment.cmd_line_options.projectoptions:
                        if cmd_arg.startswith(cmd_prefix):
                            value = cmd_arg.split('=', 1)[1]
                            new_options[i].set_value(value)
                new_options.update(self.coredata.compiler_options)
                self.coredata.compiler_options = new_options
            mlog.log('Native %s compiler: ' % lang, mlog.bold(' '.join(comp.get_exelist())), ' (%s %s)' % (comp.id, comp.version), sep='')
            if not comp.get_language() in self.coredata.external_args:
                (ext_compile_args, ext_link_args) = environment.get_args_from_envvars(comp.get_language())
                self.coredata.external_args[comp.get_language()] = ext_compile_args
                self.coredata.external_link_args[comp.get_language()] = ext_link_args
            self.build.add_compiler(comp)
            if need_cross_compiler:
                mlog.log('Cross %s compiler: ' % lang, mlog.bold(' '.join(cross_comp.get_exelist())), ' (%s %s)' % (cross_comp.id, cross_comp.version), sep='')
                self.build.add_cross_compiler(cross_comp)
            if self.environment.is_cross_build() and not need_cross_compiler:
                self.build.add_cross_compiler(comp)

    def func_find_program(self, node, args, kwargs):
        self.validate_arguments(args, 1, [str])
        required = kwargs.get('required', True)
        if not isinstance(required, bool):
            raise InvalidArguments('"required" argument must be a boolean.')
        exename = args[0]
        if exename in self.coredata.ext_progs and\
           self.coredata.ext_progs[exename].found():
            return ExternalProgramHolder(self.coredata.ext_progs[exename])
        # Search for scripts relative to current subdir.
        search_dir = os.path.join(self.environment.get_source_dir(), self.subdir)
        extprog = dependencies.ExternalProgram(exename, search_dir=search_dir)
        progobj = ExternalProgramHolder(extprog)
        self.coredata.ext_progs[exename] = extprog
        if required and not progobj.found():
            raise InvalidArguments('Program "%s" not found.' % exename)
        return progobj

    def func_find_library(self, node, args, kwargs):
        self.validate_arguments(args, 1, [str])
        required = kwargs.get('required', True)
        if not isinstance(required, bool):
            raise InvalidArguments('"required" argument must be a boolean.')
        libname = args[0]
        # We do not cache found libraries because they can come
        # and go between invocations wildly. As an example we
        # may find the 64 bit version but need instead the 32 bit
        # one that is not installed. If we cache the found path
        # then we will never found the new one if it get installed.
        # This causes a bit of a slowdown as libraries are rechecked
        # on every regen, but since it is a fast operation it should be
        # ok.
        if 'dirs' in kwargs:
            search_dirs = kwargs['dirs']
            if not isinstance(search_dirs, list):
                search_dirs = [search_dirs]
            for i in search_dirs:
                if not isinstance(i, str):
                    raise InvalidCode('Directory entry is not a string.')
                if not os.path.isabs(i):
                    raise InvalidCode('Search directory %s is not an absolute path.' % i)
        else:
            search_dirs = None
        result = self.environment.find_library(libname, search_dirs)
        extlib = dependencies.ExternalLibrary(libname, result)
        libobj = ExternalLibraryHolder(extlib)
        if required and not libobj.found():
            raise InvalidArguments('External library "%s" not found.' % libname)
        return libobj

    def func_dependency(self, node, args, kwargs):
        self.validate_arguments(args, 1, [str])
        name = args[0]
        identifier = dependencies.get_dep_identifier(name, kwargs)
        if identifier in self.coredata.deps:
            dep = self.coredata.deps[identifier]
        else:
            dep = dependencies.Dependency() # Returns always false for dep.found()
        if not dep.found():
            try:
                dep = dependencies.find_external_dependency(name, self.environment, kwargs)
            except dependencies.DependencyException:
                if 'fallback' in kwargs:
                    return self.dependency_fallback(kwargs)
                raise
        self.coredata.deps[identifier] = dep
        return DependencyHolder(dep)

    def dependency_fallback(self, kwargs):
        fbinfo = kwargs['fallback']
        check_stringlist(fbinfo)
        if len(fbinfo) != 2:
            raise InterpreterException('Fallback info must have exactly two items.')
        dirname, varname = fbinfo
        self.do_subproject(dirname, kwargs)
        return self.subprojects[dirname].get_variable_method([varname], {})

    def func_executable(self, node, args, kwargs):
        return self.build_target(node, args, kwargs, ExecutableHolder)

    def func_static_lib(self, node, args, kwargs):
        return self.build_target(node, args, kwargs, StaticLibraryHolder)

    def func_shared_lib(self, node, args, kwargs):
        return self.build_target(node, args, kwargs, SharedLibraryHolder)

    def func_library(self, node, args, kwargs):
        if self.coredata.get_builtin_option('default_library') == 'shared':
            return self.func_shared_lib(node, args, kwargs)
        return self.func_static_lib(node, args, kwargs)

    def func_jar(self, node, args, kwargs):
        return self.build_target(node, args, kwargs, JarHolder)

    def func_build_target(self, node, args, kwargs):
        if 'target_type' not in kwargs:
            raise InterpreterException('Missing target_type keyword argument')
        target_type = kwargs.pop('target_type')
        if target_type == 'executable':
            return self.func_executable(node, args, kwargs)
        elif target_type == 'shared_library':
            return self.func_shared_lib(node, args, kwargs)
        elif target_type == 'static_library':
            return self.func_static_lib(node, args, kwargs)
        elif target_type == 'library':
            return self.func_library(node, args, kwargs)
        elif target_type == 'jar':
            return self.func_jar(node, args, kwargs)
        else:
            raise InterpreterException('Unknown target_type.')

    def func_vcs_tag(self, node, args, kwargs):
        fallback = kwargs.pop('fallback', None)
        if not isinstance(fallback, str):
            raise InterpreterException('Keyword argument fallback must exist and be a string.')
        replace_string = kwargs.pop('replace_string', '@VCS_TAG@')
        regex_selector = '(.*)' # default regex selector for custom command: use complete output
        vcs_cmd = kwargs.get('command', None)
        if vcs_cmd and not isinstance(vcs_cmd, list):
            vcs_cmd = [vcs_cmd]
        source_dir = os.path.normpath(os.path.join(self.environment.get_source_dir(), self.subdir))
        if vcs_cmd:
            # Is the command an executable in path or maybe a script in the source tree?
            vcs_cmd[0] = shutil.which(vcs_cmd[0]) or os.path.join(source_dir, vcs_cmd[0])
        else:
            vcs = mesonlib.detect_vcs(source_dir)
            if vcs:
                mlog.log('Found %s repository at %s' % (vcs['name'], vcs['wc_dir']))
                vcs_cmd = vcs['get_rev'].split()
                regex_selector = vcs['rev_regex']
            else:
                vcs_cmd = [' '] # executing this cmd will fail in vcstagger.py and force to use the fallback string
        scriptfile = os.path.join(self.environment.get_script_dir(), 'vcstagger.py')
        # vcstagger.py parameters: infile, outfile, fallback, source_dir, replace_string, regex_selector, command...
        kwargs['command'] = [sys.executable, scriptfile, '@INPUT0@', '@OUTPUT0@', fallback, source_dir, replace_string, regex_selector] + vcs_cmd
        kwargs.setdefault('build_always', True)
        return self.func_custom_target(node, [kwargs['output']], kwargs)

    @stringArgs
    def func_custom_target(self, node, args, kwargs):
        if len(args) != 1:
            raise InterpreterException('Incorrect number of arguments')
        name = args[0]
        tg = CustomTargetHolder(build.CustomTarget(name, self.subdir, kwargs))
        self.add_target(name, tg.held_object)
        return tg

    @noKwargs
    def func_run_target(self, node, args, kwargs):
        if len(args) < 2:
            raise InterpreterException('Incorrect number of arguments')
        cleaned_args = []
        for i in args:
            try:
                i = i.held_object
            except AttributeError:
                pass
            if not isinstance(i, (str, build.BuildTarget, build.CustomTarget)):
                mlog.debug('Wrong type:', str(i))
                raise InterpreterException('Invalid argument to run_target.')
            cleaned_args.append(i)
        name = cleaned_args[0]
        command = cleaned_args[1]
        cmd_args = cleaned_args[2:]
        tg = RunTargetHolder(name, command, cmd_args, self.subdir)
        self.add_target(name, tg.held_object)
        return tg

    def func_generator(self, node, args, kwargs):
        gen = GeneratorHolder(self, args, kwargs)
        self.generators.append(gen)
        return gen

    def func_benchmark(self, node, args, kwargs):
        self.add_test(node, args, kwargs, False)

    def func_test(self, node, args, kwargs):
        self.add_test(node, args, kwargs, True)

    def add_test(self, node, args, kwargs, is_base_test):
        if len(args) != 2:
            raise InterpreterException('Incorrect number of arguments')
        if not isinstance(args[0], str):
            raise InterpreterException('First argument of test must be a string.')
        if not isinstance(args[1], (ExecutableHolder, JarHolder, ExternalProgramHolder)):
            raise InterpreterException('Second argument must be executable.')
        par = kwargs.get('is_parallel', True)
        if not isinstance(par, bool):
            raise InterpreterException('Keyword argument is_parallel must be a boolean.')
        cmd_args = kwargs.get('args', [])
        if not isinstance(cmd_args, list):
            cmd_args = [cmd_args]
        for i in cmd_args:
            if not isinstance(i, (str, mesonlib.File)):
                raise InterpreterException('Command line arguments must be strings')
        envlist = kwargs.get('env', [])
        if not isinstance(envlist, list):
            envlist = [envlist]
        env = {}
        for e in envlist:
            if '=' not in e:
                raise InterpreterException('Env var definition must be of type key=val.')
            (k, val) = e.split('=', 1)
            k = k.strip()
            val = val.strip()
            if ' ' in k:
                raise InterpreterException('Env var key must not have spaces in it.')
            env[k] = val
        valgrind_args = kwargs.get('valgrind_args', [])
        if not isinstance(valgrind_args, list):
            valgrind_args = [valgrind_args]
        for a in valgrind_args:
            if not isinstance(a, str):
                raise InterpreterException('Valgrind_arg not a string.')
        should_fail = kwargs.get('should_fail', False)
        if not isinstance(should_fail, bool):
            raise InterpreterException('Keyword argument should_fail must be a boolean.')
        timeout = kwargs.get('timeout', 30)
        if 'workdir' in kwargs:
            workdir = kwargs['workdir']
            if not isinstance(workdir, str):
                raise InterpreterException('Workdir keyword argument must be a string.')
            if not os.path.isabs(workdir):
                raise InterpreterException('Workdir keyword argument must be an absolute path.')
        else:
            workdir = None
        if not isinstance(timeout, int):
            raise InterpreterException('Timeout must be an integer.')
        suite = mesonlib.stringlistify(kwargs.get('suite', ''))
        if self.is_subproject():
            newsuite = []
            for s in suite:
                newsuite.append(self.subproject.replace(' ', '_').replace('.', '_') + '.' + s)
            suite = newsuite
        t = Test(args[0], suite, args[1].held_object, par, cmd_args, env, should_fail, valgrind_args, timeout, workdir)
        if is_base_test:
            self.build.tests.append(t)
            mlog.debug('Adding test "', mlog.bold(args[0]), '".', sep='')
        else:
            self.build.benchmarks.append(t)
            mlog.debug('Adding benchmark "', mlog.bold(args[0]), '".', sep='')

    @stringArgs
    def func_install_headers(self, node, args, kwargs):
        h = Headers(self.subdir, args, kwargs)
        self.build.headers.append(h)
        return h

    @stringArgs
    def func_install_man(self, node, args, kwargs):
        m = Man(self.subdir, args, kwargs)
        self.build.man.append(m)
        return m

    @noKwargs
    def func_subdir(self, node, args, kwargs):
        self.validate_arguments(args, 1, [str])
        if '..' in args[0]:
            raise InvalidArguments('Subdir contains ..')
        if self.subdir == '' and args[0] == self.subproject_dir:
            raise InvalidArguments('Must not go into subprojects dir with subdir(), use subproject() instead.')
        prev_subdir = self.subdir
        subdir = os.path.join(prev_subdir, args[0])
        if subdir in self.visited_subdirs:
            raise InvalidArguments('Tried to enter directory "%s", which has already been visited.'\
                                   % subdir)
        self.visited_subdirs[subdir] = True
        self.subdir = subdir
        try:
            os.makedirs(os.path.join(self.environment.build_dir, subdir))
        except FileExistsError:
            pass
        buildfilename = os.path.join(self.subdir, environment.build_filename)
        self.build_def_files.append(buildfilename)
        absname = os.path.join(self.environment.get_source_dir(), buildfilename)
        if not os.path.isfile(absname):
            raise InterpreterException('Nonexistant build def file %s.' % buildfilename)
        code = open(absname).read()
        assert(isinstance(code, str))
        try:
            codeblock = mparser.Parser(code).parse()
        except coredata.MesonException as me:
            me.file = buildfilename
            raise me
        self.evaluate_codeblock(codeblock)
        self.subdir = prev_subdir

    @stringArgs
    def func_install_data(self, node, args, kwargs):
        data = DataHolder(True, self.subdir, args, kwargs)
        self.build.data.append(data.held_object)
        return data

    @stringArgs
    def func_install_subdir(self, node, args, kwargs):
        if len(args) != 1:
            raise InvalidArguments('Install_subdir requires exactly one argument.')
        if not 'install_dir' in kwargs:
            raise InvalidArguments('Missing keyword argument install_dir')
        install_dir = kwargs['install_dir']
        if not isinstance(install_dir, str):
            raise InvalidArguments('Keyword argument install_dir not a string.')
        idir = InstallDir(self.subdir, args[0], install_dir)
        self.build.install_dirs.append(idir)
        return idir