dependencies: Split search_tool out of ExternalDependency

it really doesn't make sense to put this in the ExternalDependency
class. It doesn't rely on any of the state of that class, and it's
generically useful inside meson.

1 files changed, 25 insertions, 21 deletions

diff --git a/mesonbuild/dependencies/base.py b/mesonbuild/dependencies/base.py
index 956ca39..a7b23f6 100644
--- a/mesonbuild/dependencies/base.py
+++ b/mesonbuild/dependencies/base.py
@@ -77,6 +77,27 @@ class DependencyMethods(Enum):
     DUB = 'dub'
 
 
+def find_external_program(env: Environment, for_machine: MachineChoice, name: str,
+                          display_name: str, default_names: T.List[str]) -> T.Generator['ExternalProgram', None, None]:
+    """Find an external program, chcking the cross file plus any default options."""
+    # Lookup in cross or machine file.
+    potential_path = env.lookup_binary_entry(for_machine, name)
+    if potential_path is not None:
+        mlog.debug('{} binary for {} specified from cross file, native file, '
+                    'or env var as {}'.format(display_name, for_machine, potential_path))
+        yield ExternalProgram.from_entry(name, potential_path)
+        # We never fallback if the user-specified option is no good, so
+        # stop returning options.
+        return
+    mlog.debug('{} binary missing from cross or native file, or env var undefined.'.format(display_name))
+    # Fallback on hard-coded defaults.
+    # TODO prefix this for the cross case instead of ignoring thing.
+    if env.machines.matches_build_machine(for_machine):
+        for potential_path in default_names:
+            mlog.debug('Trying a default {} fallback at'.format(display_name), potential_path)
+            yield ExternalProgram(potential_path, silent=True)
+
+
 class Dependency:
 
     @classmethod
@@ -353,25 +374,6 @@ class ExternalDependency(Dependency, HasNativeKwarg):
                         raise DependencyException(m.format(self.name, not_found, self.version))
                     return
 
-    # Create an iterator of options
-    def search_tool(self, name, display_name, default_names):
-        # Lookup in cross or machine file.
-        potential_path = self.env.lookup_binary_entry(self.for_machine, name)
-        if potential_path is not None:
-            mlog.debug('{} binary for {} specified from cross file, native file, '
-                       'or env var as {}'.format(display_name, self.for_machine, potential_path))
-            yield ExternalProgram.from_entry(name, potential_path)
-            # We never fallback if the user-specified option is no good, so
-            # stop returning options.
-            return
-        mlog.debug('{} binary missing from cross or native file, or env var undefined.'.format(display_name))
-        # Fallback on hard-coded defaults.
-        # TODO prefix this for the cross case instead of ignoring thing.
-        if self.env.machines.matches_build_machine(self.for_machine):
-            for potential_path in default_names:
-                mlog.debug('Trying a default {} fallback at'.format(display_name), potential_path)
-                yield ExternalProgram(potential_path, silent=True)
-
 
 class NotFoundDependency(Dependency):
     def __init__(self, environment):
@@ -437,7 +439,9 @@ class ConfigToolDependency(ExternalDependency):
         if not isinstance(versions, list) and versions is not None:
             versions = listify(versions)
         best_match = (None, None)
-        for potential_bin in self.search_tool(self.tool_name, self.tool_name, self.tools):
+        for potential_bin in find_external_program(
+                self.env, self.for_machine, self.tool_name,
+                self.tool_name, self.tools):
             if not potential_bin.found():
                 continue
             tool = potential_bin.get_command()
@@ -561,7 +565,7 @@ class PkgConfigDependency(ExternalDependency):
         else:
             assert PkgConfigDependency.class_pkgbin[self.for_machine] is None
             mlog.debug('Pkg-config binary for %s is not cached.' % self.for_machine)
-            for potential_pkgbin in self.search_tool('pkgconfig', 'Pkg-config', environment.default_pkgconfig):
+            for potential_pkgbin in find_external_program(self.env, self.for_machine, 'pkgconfig', 'Pkg-config', environment.default_pkgconfig):
                 mlog.debug('Trying pkg-config binary {} for machine {} at {}'
                            .format(potential_pkgbin.name, self.for_machine, potential_pkgbin.command))
                 version_if_ok = self.check_pkgconfig(potential_pkgbin)