Add support for "else if" in gyp conditions

Right now, a gyp condition consists of exactly two or three parts:

  [cond_expr, true_dict]
  [cond_expr, true_dict, false_dict]

This means if we want to have an "else if" condition, it needs to be inside a
nested 'conditions' list inside the false_dict.  This leads to unnecessarily
deep levels of nesting in gyp files.

This commit makes it so that if the 'false_dict' is not a dict, then we will
treat it as another cond_expr.  We keep looping like this until we find a
false_dict, or until we reach the end of the list.

This means we can now have conditions that look like this:

  [cond_expr1, true_dict1, cond_expr2, true_dict2, false_dict]

or:

  [cond_expr1, true_dict1, cond_expr2, true_dict2, cond_expr3, true_dict3]

BUG=
R=scottmg@chromium.org

Review URL: https://codereview.chromium.org/601353002

git-svn-id: http://gyp.googlecode.com/svn/trunk@2004 78cadc50-ecff-11dd-a971-7dbc132099af

pylib/gyp/input.py

@@ -341,7 +341,8 @@ def ProcessToolsetsInDict(data):
     for condition in data['conditions']:
       if type(condition) is list:
         for condition_dict in condition[1:]:
-          ProcessToolsetsInDict(condition_dict)
+          if type(condition_dict) is dict:
+            ProcessToolsetsInDict(condition_dict)
 
 
 # TODO(mark): I don't love this name.  It just means that it's going to load
@@ -1037,17 +1038,40 @@ def EvalCondition(condition, conditions_key, phase, variables, build_file):
   that nothing should be used."""
   if type(condition) is not list:
     raise GypError(conditions_key + ' must be a list')
-  if len(condition) != 2 and len(condition) != 3:
+  if len(condition) < 2:
     # It's possible that condition[0] won't work in which case this
     # attempt will raise its own IndexError.  That's probably fine.
     raise GypError(conditions_key + ' ' + condition[0] +
-                   ' must be length 2 or 3, not ' + str(len(condition)))
+                   ' must be at least length 2, not ' + str(len(condition)))
+
+  i = 0
+  result = None
+  while i < len(condition):
+    cond_expr = condition[i]
+    true_dict = condition[i + 1]
+    if type(true_dict) is not dict:
+      raise GypError('{} {} must be followed by a dictionary, not {}'.format(
+        conditions_key, cond_expr, type(true_dict)))
+    if len(condition) > i + 2 and type(condition[i + 2]) is dict:
+      false_dict = condition[i + 2]
+      i = i + 3
+      if i != len(condition):
+        raise GypError('{} {} has {} unexpected trailing items'.format(
+          conditions_key, cond_expr, len(condition) - i))
+    else:
+      false_dict = None
+      i = i + 2
+    if result == None:
+      result = EvalSingleCondition(
+          cond_expr, true_dict, false_dict, phase, variables, build_file)
+
+  return result
 
-  [cond_expr, true_dict] = condition[0:2]
-  false_dict = None
-  if len(condition) == 3:
-    false_dict = condition[2]
 
+def EvalSingleCondition(
+    cond_expr, true_dict, false_dict, phase, variables, build_file):
+  """Returns true_dict if cond_expr evaluates to true, and false_dict
+  otherwise."""
   # Do expansions on the condition itself.  Since the conditon can naturally
   # contain variable references without needing to resort to GYP expansion
   # syntax, this is of dubious value for variables, but someone might want to

test/conditions/elseif/elseif.gyp

@@ -0,0 +1,43 @@
+# Copyright (c) 2014 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+{
+  'targets': [
+    {
+      'variables': { 'test_var': 0 },
+      'target_name': 'program0',
+      'type': 'executable',
+      'sources': [ 'program.cc' ],
+      'includes': [ 'elseif_conditions.gypi' ],
+    },
+    {
+      'variables': { 'test_var': 1 },
+      'target_name': 'program1',
+      'type': 'executable',
+      'sources': [ 'program.cc' ],
+      'includes': [ 'elseif_conditions.gypi' ],
+    },
+    {
+      'variables': { 'test_var': 2 },
+      'target_name': 'program2',
+      'type': 'executable',
+      'sources': [ 'program.cc' ],
+      'includes': [ 'elseif_conditions.gypi' ],
+    },
+    {
+      'variables': { 'test_var': 3 },
+      'target_name': 'program3',
+      'type': 'executable',
+      'sources': [ 'program.cc' ],
+      'includes': [ 'elseif_conditions.gypi' ],
+    },
+    {
+      'variables': { 'test_var': 4 },
+      'target_name': 'program4',
+      'type': 'executable',
+      'sources': [ 'program.cc' ],
+      'includes': [ 'elseif_conditions.gypi' ],
+    },
+  ],
+}

test/conditions/elseif/elseif_bad1.gyp

@@ -0,0 +1,20 @@
+# Copyright (c) 2014 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# Trigger an error because of two consecutive string conditions.
+
+{
+  'targets': [
+    {
+      'variables': { 'test_var': 0 },
+      'target_name': 'program',
+      'type': 'executable',
+      'sources': [ 'program.cc' ],
+      'conditions': [
+        ['test_var==0', 'test_var==1', {
+        }],
+      ],
+    },
+  ],
+}

test/conditions/elseif/elseif_bad2.gyp

@@ -0,0 +1,22 @@
+# Copyright (c) 2014 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# Trigger an error because of two consecutive string conditions, even if the
+# conditions are not actually evaluated.
+
+{
+  'targets': [
+    {
+      'variables': { 'test_var': 0 },
+      'target_name': 'program',
+      'type': 'executable',
+      'sources': [ 'program.cc' ],
+      'conditions': [
+        ['test_var==0', {
+        }, 'test_var==1', 'test_var==2', {
+        }],
+      ],
+    },
+  ],
+}

test/conditions/elseif/elseif_bad3.gyp

@@ -0,0 +1,23 @@
+# Copyright (c) 2014 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# Trigger an error because there are unexpected trailing items in a condition.
+
+{
+  'targets': [
+    {
+      'variables': { 'test_var': 0 },
+      'target_name': 'program',
+      'type': 'executable',
+      'sources': [ 'program.cc' ],
+      'conditions': [
+        ['test_var==0' {
+        }, 'test_var==1', {
+        }, {
+        }, 'test_var==2', {
+        }],
+      ],
+    },
+  ],
+}

test/conditions/elseif/elseif_conditions.gypi

@@ -0,0 +1,15 @@
+{
+  'conditions': [
+    ['test_var==0', {
+      'defines': ['FOO="first_if"'],
+    }, 'test_var==1', {
+      'defines': ['FOO="first_else_if"'],
+    }, 'test_var==2', {
+      'defines': ['FOO="second_else_if"'],
+    }, 'test_var==3', {
+      'defines': ['FOO="third_else_if"'],
+    }, {
+      'defines': ['FOO="last_else"'],
+    }],
+  ],
+}

test/conditions/elseif/gyptest_elseif.py

@@ -0,0 +1,33 @@
+#!/usr/bin/env python
+
+# Copyright (c) 2014 Google Inc. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""
+Verify that "else-if" conditions work.
+"""
+
+import TestGyp
+
+test = TestGyp.TestGyp()
+
+test.run_gyp('elseif.gyp')
+test.build('elseif.gyp', test.ALL)
+test.run_built_executable(
+    'program0', stdout='first_if\n')
+test.run_built_executable(
+    'program1', stdout='first_else_if\n')
+test.run_built_executable(
+    'program2', stdout='second_else_if\n')
+test.run_built_executable(
+    'program3', stdout='third_else_if\n')
+test.run_built_executable(
+    'program4', stdout='last_else\n')
+
+# Verify that bad condition blocks fail at gyp time.
+test.run_gyp('elseif_bad1.gyp', status=1, stderr=None)
+test.run_gyp('elseif_bad2.gyp', status=1, stderr=None)
+test.run_gyp('elseif_bad3.gyp', status=1, stderr=None)
+
+test.pass_test()

test/conditions/elseif/program.cc

@@ -0,0 +1,10 @@
+// Copyright (c) 2014 Google Inc. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <stdio.h>
+
+int main() {
+  printf("%s\n", FOO);
+  return 0;
+}