Add a Protoc C++ tool.

Example:

    prog = cxx.Program('prog')
    protos = builder.tools.Protoc(sources = ['myproto.proto'])
    prog.custom += [protos]

To make this work, protoc is now always executed in the top level of the
build directory. This is kind of gross as we have to make sure all paths
are relative to the root, rather than cwd. The alternative is running
protoc once for each language, which would be fine, but the current
thing is working.

ambuild2/frontend/v2_2/tools/__init__.py

@@ -2,3 +2,4 @@
 
 from ambuild2.frontend.v2_2.tools.fxc import FxcJob as FXC
 from ambuild2.frontend.v2_2.tools.protoc import DetectProtoc as DetectProtoc
+from ambuild2.frontend.v2_2.tools.protoc import ProtocJob as Protoc

ambuild2/frontend/v2_2/tools/protoc.py

@@ -20,7 +20,9 @@
 import subprocess
 from ambuild2 import util
 from ambuild2.frontend.version import Version
+from ambuild2.frontend import paths
 
+# Helper for building AddCommand() invocations for protoc.
 class ProtocRunner(object):
     def __init__(self, protoc, builder, includes):
         self.protoc = protoc
@@ -46,8 +48,12 @@ def AddOutput(self, language, folder):
         }
         self.gen_map[language] = {}
 
-        out_build_path = os.path.relpath(folder.path, self.builder.buildFolder)
-        self.argv += ['--{}_out={}'.format(language, out_build_path)]
+        if folder is None:
+            folder_path = '.'
+        else:
+            folder_path = folder.path
+
+        self.argv += ['--{}_out={}'.format(language, folder_path)]
 
     def AddSource(self, source_path):
         source_name = os.path.basename(source_path)
@@ -59,9 +65,11 @@ def AddSource(self, source_path):
         gen_file_list = []
         gen_file_map = {}
         for language in self.languages:
+            folder = self.languages[language]['folder']
+
             gen_info = gen_file_map.setdefault(language, {
-                'sources': [],
-                'headers': [],
+                'sources': 0,
+                'headers': 0,
             })
             gen_source_names = []
             gen_header_names = []
@@ -79,13 +87,13 @@ def AddSource(self, source_path):
             else:
                 raise Exception('Language not supported yet: {}'.format(language))
 
-            gen_file_list += gen_source_names
-            gen_file_list += gen_header_names
+            for file in gen_source_names + gen_header_names:
+                gen_file_list += [paths.Join(folder, file)]
 
-            gen_info['sources'] += gen_source_names
-            gen_info['headers'] += gen_header_names
+            gen_info['sources'] += len(gen_source_names)
+            gen_info['headers'] += len(gen_header_names)
 
-        dep_file = '{}.d'.format(source_name)
+        dep_file = paths.Join(folder, '{}.d'.format(source_name))
         argv = self.argv + [
             '--dependency_out={}'.format(dep_file),
             source_path,
@@ -96,16 +104,17 @@ def AddSource(self, source_path):
                                               outputs = gen_file_list,
                                               dep_type = 'md',
                                               dep_file = dep_file,
-                                              shared_outputs = [dep_file])
+                                              shared_outputs = [dep_file],
+                                              folder = None)
 
         # Translate the list of generated output entries.
         cursor = 0
         for language in self.languages:
             gen_info = gen_file_map[language]
-            gen_sources = gen_entries[cursor:cursor + len(gen_info['sources'])]
+            gen_sources = gen_entries[cursor:cursor + gen_info['sources']]
             cursor += len(gen_sources)
 
-            gen_headers = gen_entries[cursor:cursor + len(gen_info['headers'])]
+            gen_headers = gen_entries[cursor:cursor + gen_info['headers']]
             cursor += len(gen_headers)
 
             self.gen_map[language].setdefault('sources', []).extend(gen_sources)
@@ -115,11 +124,13 @@ def AddSource(self, source_path):
         # Should be one entry remaining, for the .d file.
         assert (cursor == len(gen_entries))
 
+# Named tuple for protoc.StaticLibrary() results.
 class ProtocCppNode(object):
     def __init__(self, lib, headers):
         self.lib = lib
         self.headers = headers
 
+# Like cpp.Compiler, but for protobufs.
 class Protoc(object):
     def __init__(self, path, name, version):
         super(Protoc, self).__init__()
@@ -168,6 +179,8 @@ def StaticLibrary(self, name, builder, cxx, sources, includes = []):
         out = builder.Add(binary)
         return ProtocCppNode(out, gen_map['cpp']['headers'])
 
+FoundProtocMap = set()
+
 def DetectProtoc(**kwargs):
     path = kwargs.pop('path', None)
     if len(kwargs):
@@ -188,6 +201,30 @@ def DetectProtoc(**kwargs):
     name = parts[0]
     version = Version(parts[1])
 
-    util.con_out(util.ConsoleHeader, 'found protoc {}-{}'.format(name, version))
+    if path not in FoundProtocMap:
+        util.con_out(util.ConsoleHeader, 'found protoc {}-{}'.format(name, version))
+        FoundProtocMap.add(path)
 
     return Protoc(path, name, version)
+
+class ProtocTool(object):
+    def __init__(self):
+        pass
+
+    def evaluate(self, cmd):
+        gen_map = cmd.data.protoc.Generate(builder = cmd.context,
+                                           sources = cmd.data.sources,
+                                           outputs = [('cpp', cmd.localFolderNode)])
+        cmd.sourcedeps += gen_map['cpp']['sources']
+        cmd.sourcedeps += gen_map['cpp']['headers']
+        for source in gen_map['cpp']['sources']:
+            cmd.sources += [os.path.join(cmd.context.buildPath, source.path)]
+
+class ProtocJob(object):
+    def __init__(self, protoc = None, sources = []):
+        if protoc is None:
+            self.protoc = DetectProtoc()
+        else:
+            self.protoc = protoc.clone()
+        self.sources = sources[:]
+        self.tool = ProtocTool()