Add support to integer modulo operator

Having support for the '%' operator makes it easier to implement
even/odd version checks, like:

    enable_debug = get_option('enable-debug')
    if enable_debug == 'auto'
      if minor_version % 2 == 0
        enable_debug = 'minimum'
      else
        enable_debug = 'yes'
      endif
    endif

which would be impossible without resorting to less obvious long-hand
forms like:

  a - (b * (a / b))

1 files changed, 8 insertions, 1 deletions

diff --git a/mesonbuild/mparser.py b/mesonbuild/mparser.py
index 2f0eb2d..f593c8e 100644
--- a/mesonbuild/mparser.py
+++ b/mesonbuild/mparser.py
@@ -58,6 +58,7 @@ class Lexer:
             ('plus', re.compile(r'\+')),
             ('dash', re.compile(r'-')),
             ('star', re.compile(r'\*')),
+            ('percent', re.compile(r'\%')),
             ('fslash', re.compile(r'/')),
             ('colon', re.compile(r':')),
             ('equal', re.compile(r'==')),
@@ -434,11 +435,17 @@ class Parser:
         return left
 
     def e5sub(self):
-        left = self.e5mul()
+        left = self.e5mod()
         if self.accept('dash'):
             return ArithmeticNode(left.lineno, left.colno, 'sub', left, self.e5sub())
         return left
 
+    def e5mod(self):
+        left = self.e5mul()
+        if self.accept('percent'):
+            return ArithmeticNode(left.lineno, left.colno, 'mod', left, self.e5mod())
+        return left
+
     def e5mul(self):
         left = self.e5div()
         if self.accept('star'):