1 files changed, 91 insertions, 0 deletions
diff --git a/mesonbuild/depfile.py b/mesonbuild/depfile.py
new file mode 100644
index 0000000..d346136
--- /dev/null
+++ b/mesonbuild/depfile.py
@@ -0,0 +1,91 @@
+# Copyright 2019 Red Hat, Inc.
+# 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.
+from __future__ import annotations
+
+import typing as T
+
+
+def parse(lines: T.Iterable[str]) -> T.List[T.Tuple[T.List[str], T.List[str]]]:
+    rules: T.List[T.Tuple[T.List[str], T.List[str]]] = []
+    targets: T.List[str] = []
+    deps: T.List[str] = []
+    in_deps = False
+    out = ''
+    for line in lines:
+        if not line.endswith('\n'):
+            line += '\n'
+        escape = None
+        for c in line:
+            if escape:
+                if escape == '$' and c != '$':
+                    out += '$'
+                if escape == '\\' and c == '\n':
+                    continue
+                out += c
+                escape = None
+                continue
+            if c in {'\\', '$'}:
+                escape = c
+                continue
+            elif c in {' ', '\n'}:
+                if out != '':
+                    if in_deps:
+                        deps.append(out)
+                    else:
+                        targets.append(out)
+                out = ''
+                if c == '\n':
+                    rules.append((targets, deps))
+                    targets = []
+                    deps = []
+                    in_deps = False
+                continue
+            elif c == ':':
+                targets.append(out)
+                out = ''
+                in_deps = True
+                continue
+            out += c
+    return rules
+
+class Target(T.NamedTuple):
+
+    deps: T.Set[str]
+
+
+class DepFile:
+    def __init__(self, lines: T.Iterable[str]):
+        rules = parse(lines)
+        depfile: T.Dict[str, Target] = {}
+        for (targets, deps) in rules:
+            for target in targets:
+                t = depfile.setdefault(target, Target(deps=set()))
+                for dep in deps:
+                    t.deps.add(dep)
+        self.depfile = depfile
+
+    def get_all_dependencies(self, name: str, visited: T.Optional[T.Set[str]] = None) -> T.List[str]:
+        deps: T.Set[str] = set()
+        if not visited:
+            visited = set()
+        if name in visited:
+            return []
+        visited.add(name)
+
+        target = self.depfile.get(name)
+        if not target:
+            return []
+        deps.update(target.deps)
+        for dep in target.deps:
+            deps.update(self.get_all_dependencies(dep, visited))
+        return sorted(deps)