gclient: implement conditions for hooks

Bug: 570091
Change-Id: I5a489f9f9cbc5384b720685264aa918573234cf5
Reviewed-on: https://chromium-review.googlesource.com/544965
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Paweł Hajdan Jr. <phajdan.jr@chromium.org>

gclient.py

@@ -139,7 +139,8 @@ def ToGNString(value, allow_dicts = True):
 class Hook(object):
   """Descriptor of command ran before/after sync or on demand."""
 
-  def __init__(self, action, pattern=None, name=None, cwd=None):
+  def __init__(self, action, pattern=None, name=None, cwd=None, condition=None,
+               variables=None):
     """Constructor.
 
     Arguments:
@@ -147,16 +148,26 @@ class Hook(object):
       pattern (basestring regex): noop with git; deprecated
       name (basestring): optional name; no effect on operation
       cwd (basestring): working directory to use
+      condition (basestring): condition when to run the hook
+      variables (dict): variables for evaluating the condition
     """
     self._action = gclient_utils.freeze(action)
     self._pattern = pattern
     self._name = name
     self._cwd = cwd
+    self._condition = condition
+    self._variables = variables
 
   @staticmethod
-  def from_dict(d):
+  def from_dict(d, variables=None):
     """Creates a Hook instance from a dict like in the DEPS file."""
-    return Hook(d['action'], d.get('pattern'), d.get('name'), d.get('cwd'))
+    return Hook(
+        d['action'],
+        d.get('pattern'),
+        d.get('name'),
+        d.get('cwd'),
+        d.get('condition'),
+        variables=variables)
 
   @property
   def action(self):
@@ -178,7 +189,11 @@ class Hook(object):
     return bool([f for f in file_list if pattern.search(f)])
 
   def run(self, root):
-    """Executes the hook's command."""
+    """Executes the hook's command (provided the condition is met)."""
+    if (self._condition and
+        not gclient_eval.EvaluateCondition(self._condition, self._variables)):
+      return
+
     cmd = list(self._action)
     if cmd[0] == 'python':
       # If the hook specified "python" as the first item, the action is a
@@ -782,8 +797,9 @@ class Dependency(gclient_utils.WorkItem, DependencySettings):
         hooks_to_run.append(hook)
 
     if self.recursion_limit:
-      self._pre_deps_hooks = [Hook.from_dict(hook) for hook in
-                              local_scope.get('pre_deps_hooks', [])]
+      self._pre_deps_hooks = [
+          Hook.from_dict(hook, variables=self._vars) for hook in
+          local_scope.get('pre_deps_hooks', [])]
 
     self.add_dependencies_and_close(
         deps_to_add, hooks_to_run, orig_deps_to_add=orig_deps_to_add)
@@ -803,7 +819,8 @@ class Dependency(gclient_utils.WorkItem, DependencySettings):
         self.add_dependency(dep)
     for dep in (orig_deps_to_add or deps_to_add):
       self.add_orig_dependency(dep)
-    self._mark_as_parsed([Hook.from_dict(h) for h in hooks])
+    self._mark_as_parsed(
+        [Hook.from_dict(h, variables=self._vars) for h in hooks])
 
   def findDepsFromNotAllowedHosts(self):
     """Returns a list of depenecies from not allowed hosts.
@@ -994,7 +1011,6 @@ class Dependency(gclient_utils.WorkItem, DependencySettings):
     for hook in self.pre_deps_hooks:
       hook.run(self.root.root_dir)
 
-
   def subtree(self, include_all):
     """Breadth first recursion excluding root node."""
     dependencies = self.dependencies

gclient_eval.py

@@ -23,6 +23,10 @@ _GCLIENT_HOOKS_SCHEMA = [{
 
     # Working directory where to execute the hook.
     schema.Optional('cwd'): basestring,
+
+    # Optional condition string. The hook will only be run
+    # if the condition evaluates to True.
+    schema.Optional('condition'): basestring,
 }]
 
 _GCLIENT_SCHEMA = schema.Schema({

testing_support/fake_repos.py

@@ -298,7 +298,7 @@ class FakeReposBase(object):
 
 class FakeRepos(FakeReposBase):
   """Implements populateGit()."""
-  NB_GIT_REPOS = 6
+  NB_GIT_REPOS = 7
 
   def populateGit(self):
     # Testing:
@@ -507,6 +507,27 @@ recursedeps = [
       'origin': 'git/repo_6@1\n',
     })
 
+    self._commit_git('repo_7', {
+      'DEPS': """
+vars = {
+  'true_var': 'True',
+  'false_var': 'true_var and False',
+}
+hooks = [
+  {
+    'action': ['python', '-c',
+               'open(\\'src/should_run\\', \\'w\\').write(\\'should_run\\')'],
+    'condition': 'true_var or True',
+  },
+  {
+    'action': ['python', '-c',
+               'open(\\'src/should_not_run\\', \\'w\\').write(\\'should_not_run\\')'],
+    'condition': 'false_var',
+  },
+]""",
+      'origin': 'git/repo_7@1\n',
+    })
+
 
 class FakeRepoSkiaDEPS(FakeReposBase):
   """Simulates the Skia DEPS transition in Chrome."""

tests/gclient_smoketest.py

@@ -461,6 +461,15 @@ class GClientSmokeGIT(GClientSmokeBase):
     tree['src/git_hooked2'] = 'git_hooked2'
     self.assertTree(tree)
 
+  def testRunHooksCondition(self):
+    if not self.enabled:
+      return
+    self.gclient(['config', self.git_base + 'repo_7', '--name', 'src'])
+    self.gclient(['sync', '--deps', 'mac'])
+    tree = self.mangle_git_tree(('repo_7@1', 'src'))
+    tree['src/should_run'] = 'should_run'
+    self.assertTree(tree)
+
   def testPreDepsHooks(self):
     if not self.enabled:
       return