Fix use of LOAD= with WantSystemLib() (we could blow up if a variable

hadn't been added to the config) and extend use of LOAD= into submodules:
* Add a ChromeLoadSConscriptModules() method that encapsulates the
  conditional logic, and makes things more readable by specifying
  component names as keyword arguments, not hard-coding the logic
  as a series of if-tests.
* Put the ChromeLoadSConscriptModules() logic in a Tool module in
  site_scons/site_tools, so it doesn't clutter up
  build/SConscript.main directly.
* Move env.WantSystemLib() calls into the individual *.scons files,
  so we call them each time (or not, based one LOAD=) and the config
  itself just returns if the system library is requested and we
  don't need to build anything locally.
* Move the settings where a library name changes based on whether or
  not the system lib is being used into the using_*.scons files,
  so they're available to clients independently of whether or not the
  component's *.scons configuration is loaded.
* While here:  rename the affected third_party SConscript files:
  third_party/libjpeg/SConscript => third_party/libjpeg/libjpeg.scons
  third_party/libxml/SConscript => third_party/libxml/libxml.scons
  third_party/libxslt/SConscript => third_party/libxslt/libxslt.scons
* While here:  move the Chrome{Program,SharedLibrary}() etc. builder
  definitions from build/SConscript.main to a new too
  Ad the ChromeLoadSConscriptModules() logic in a Tool module,
  to remove more clutter from build/SConscript.main.
Review URL: http://codereview.chromium.org/11430

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@5820 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 116 insertions, 0 deletions

diff --git a/site_scons/site_tools/chromium_builders.py b/site_scons/site_tools/chromium_builders.py
new file mode 100644
index 0000000..a5c3964
--- /dev/null
+++ b/site_scons/site_tools/chromium_builders.py
@@ -0,0 +1,35 @@
+# Copyright (c) 2006-2008 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.
+
+"""
+Tool module for adding, to a construction environment, Chromium-specific
+wrappers around Hammer builders.  This gives us a central place for any
+customization we need to make to the different things we build.
+"""
+
+def generate(env):
+  def ChromeProgram(env, *args, **kw):
+    return env.ComponentProgram(*args, **kw)
+  env.AddMethod(ChromeProgram)
+
+  def ChromeTestProgram(env, *args, **kw):
+    return env.ComponentTestProgram(*args, **kw)
+  env.AddMethod(ChromeTestProgram)
+
+  def ChromeStaticLibrary(env, *args, **kw):
+    kw['COMPONENT_STATIC'] = True
+    return env.ComponentLibrary(*args, **kw)
+  env.AddMethod(ChromeStaticLibrary)
+
+  def ChromeSharedLibrary(env, *args, **kw):
+    kw['COMPONENT_STATIC'] = False
+    return [env.ComponentLibrary(*args, **kw)[0]]
+  env.AddMethod(ChromeSharedLibrary)
+
+  def ChromeObject(env, *args, **kw):
+    return env.ComponentObject(*args, **kw)
+  env.AddMethod(ChromeObject)
+
+def exists(env):
+  return True
diff --git a/site_scons/site_tools/chromium_load_component.py b/site_scons/site_tools/chromium_load_component.py
new file mode 100644
index 0000000..24c6e03
--- /dev/null
+++ b/site_scons/site_tools/chromium_load_component.py
@@ -0,0 +1,81 @@
+# Copyright (c) 2006-2008 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.
+
+"""
+Tool module for managing conditional loading of components in a
+Chromium build (i.e., the LOAD= command-line argument).
+"""
+
+from SCons.Script import *
+
+def generate(env):
+
+  class LoadComponent:
+    """
+    Class for deciding if a given component name is to be included
+    based on a list of included names, optionally prefixed with '-'
+    to exclude the name.
+    """
+    def __init__(self, load=[], names=[]):
+      """
+      Initialize a class with a list of names for possible loading.
+
+      Arguments:
+        load:  list of elements in the LOAD= specification
+        names:  name(s) that represent this global collection
+      """
+      self.included = set([c for c in load if not c.startswith('-')])
+      self.excluded = set([c[1:] for c in load if c.startswith('-')])
+
+      # Remove the global collection name(s) from the included list.
+      # This supports (e.g.) specifying 'webkit' so the top-level of the
+      # hierarchy will read up the subsystem, and then 'test_shell'
+      # as one specific sub-component within 'webkit'.
+      self.included = self.included - set(names)
+
+      if not self.included:
+        self.included = ['all']
+
+    def __call__(self, component):
+      """
+      Returns True if the specified component should be loaded,
+      based on the initialized included and excluded lists.
+      """
+      return (component in self.included or
+              ('all' in self.included and not component in self.excluded))
+
+  def ChromiumLoadComponentSConscripts(env, *args, **kw):
+    """
+    Returns a list of SConscript files to load, based on LOAD=.
+
+    SConscript files specified without keyword arguments are returned
+    unconditionally.  SConscript files specified with a keyword arguments
+    (e.g. chrome = 'chrome.scons') are loaded only if the LOAD= line
+    indicates their keyword argument should be included in the load.
+    """
+    try:
+        load = ARGUMENTS.get('LOAD').split(',')
+    except AttributeError:
+        load = []
+
+    try:
+        names = kw['LOAD_NAMES']
+    except KeyError:
+        names = []
+    else:
+        del kw['LOAD_NAMES']
+
+    load_component = LoadComponent(load, names)
+
+    result = list(args)
+    for module, sconscript in kw.items():
+      if load_component(module):
+        result.append(sconscript)
+
+    return Flatten(result)
+
+  env.AddMethod(ChromiumLoadComponentSConscripts)
+
+def exists(env):
+  return True