Improvements to scons build for beast.

* Common code extracted to Python directories.
* Read ~/.scons file for scons environment defaults.
* Override scons settings with shell environment variables.
* New "tags" for debug, nodebug, optimize, nooptimize builds.
* Universal platform detection.
* Default value of environment variables set through prefix dictionaries.
* Check for correct Boost value and fail otherwise.
* Extract git describe --tags into a preprocesor variable, -DTIP_BRANCH
* More colors - blue for unchanged defaults, green for changed defaults, red for error.
* Contain unit tests for non-obvious stuff.
* Check to see that boost libraries have been built.
* Right now, we accept both .dylib and .a versions but it'd be easy to enforce .a only.

python/beast/env/AddCommonFlags.py

@@ -0,0 +1,11 @@
+from __future__ import absolute_import, division, print_function, unicode_literals
+
+from beast.util import Boost
+from beast.util import Git
+
+def add_common_flags(env):
+    git_flag = '-DTIP_BRANCH="%s"' % Git.describe()
+    env['CPPFLAGS'] = '%s %s' % (env['CPPFLAGS'], git_flag)
+    env['CPPPATH'].insert(0, Boost.CPPPATH)
+    env['LIBPATH'].append(Boost.LIBPATH)
+    env['BOOST_HOME'] = Boost.CPPPATH

python/beast/env/AddUserEnv.py

@@ -0,0 +1,38 @@
+from __future__ import absolute_import, division, print_function, unicode_literals
+
+import os
+import shlex
+
+from beast.env.ReadEnvFile import read_env_file
+from beast.util.String import is_string
+from beast.util.Terminal import warn
+
+_BAD_VARS_ERROR = """
+the following variables appearing in %s were not understood:
+  %s"""
+
+def add_user_env(env, dotfile, print=print):
+    df = os.path.expanduser(dotfile)
+    try:
+        with open(df, 'r') as f:
+            dotvars = read_env_file(f.read())
+    except IOError:
+        if os.path.exists(df):
+            warn("Dotfile %s exists but can't be read." % dotfile, print)
+        dotvars = {}
+
+    bad_names = []
+    for name, value in dotvars.items():
+        if name in env:
+            if is_string(env[name]):
+                env[name] = value
+            else:
+                env[name] = shlex.split(value)
+        else:
+            bad_names.append(name)
+    if bad_names:
+        error = _BAD_VARS_ERROR % (dotfile, '\n  '.join(bad_names))
+        warn(error, print)
+
+    for name, default in env.items():
+        env[name] = os.environ.get(name, default)

python/beast/env/Print.py

@@ -0,0 +1,41 @@
+from __future__ import absolute_import, division, print_function, unicode_literals
+
+import textwrap
+
+from beast.util import String
+from beast.util import Terminal
+
+FIELD_WIDTH = 10
+LINE_WIDTH = 69
+
+EMPTY_NAME = ' ' * FIELD_WIDTH
+
+TEXT_WRAPPER = textwrap.TextWrapper(
+    break_long_words=False,
+    break_on_hyphens=False,
+    width=LINE_WIDTH,
+)
+
+DISPLAY_EMPTY_ENVS = True
+
+def print_build_vars(name, value, same, print=print):
+    """Pretty-print values as a build configuration."""
+    name = '%s' % name.rjust(FIELD_WIDTH)
+    color = Terminal.blue if same else Terminal.green
+
+    for line in TEXT_WRAPPER.wrap(String.stringify(value, ' ')):
+        print(' '.join([name, color(line)]))
+        name = EMPTY_NAME
+
+def print_cmd_line(s, target, source, env):
+    print(EMPTY_NAME + Terminal.blue(String.stringify(target)))
+
+def print_build_config(env, original, print=print):
+    print('\nConfiguration:')
+    for name, value in env.items():
+        if value or DISPLAY_EMPTY_ENVS:
+            same = (value == original[name])
+            if not same:
+                print('"%s" != "%s"' % (value, original[name]))
+            print_build_vars(name, value, same, print=print)
+    print()

python/beast/env/ReadEnvFile.py

@@ -0,0 +1,34 @@
+from __future__ import absolute_import, division, print_function, unicode_literals
+
+import json
+import re
+
+from beast.util import String
+from beast.util.Terminal import warn
+
+ENV_LINE_MATCH = re.compile(r'(?: export \s+)? \s* ([^=\s]*) \s* = (.*)',
+                            re.VERBOSE)
+
+def read_env_file(data, print=print):
+    try:
+        return json.loads(data)
+    except ValueError:
+        pass
+
+    bad_lines = []
+    results = {}
+    for number, raw_line in enumerate(data.splitlines()):
+        line = String.remove_comment(raw_line).strip()
+        if line:
+            match = ENV_LINE_MATCH.match(line)
+            if match:
+                name, value = match.groups()
+                results[name.strip()] = String.remove_quotes(value.strip())
+            else:
+                bad_lines.append([number, raw_line])
+    if bad_lines:
+         warn("Didn't understand the following environment file lines:", print)
+         for number, line in bad_lines:
+             print('%d. >>> %s' % (number + 1, line))
+
+    return results

python/beast/env/ReadEnvFile_test.py

@@ -0,0 +1,51 @@
+from __future__ import absolute_import, division, print_function, unicode_literals
+
+from unittest import TestCase
+from beast.env.ReadEnvFile import read_env_file
+
+from beast.util import Terminal
+Terminal.CAN_CHANGE_COLOR = False
+
+JSON = """
+{
+  "FOO": "foo",
+  "BAR": "bar bar bar",
+  "CPPFLAGS": "-std=c++11 -frtti -fno-strict-aliasing -DWOMBAT"
+}"""
+
+ENV = """
+# An env file.
+
+FOO=foo
+export BAR="bar bar bar"
+CPPFLAGS=-std=c++11 -frtti -fno-strict-aliasing -DWOMBAT
+
+# export BAZ=baz should be ignored.
+
+"""
+
+RESULT = {
+    'FOO': 'foo',
+    'BAR': 'bar bar bar',
+    'CPPFLAGS': '-std=c++11 -frtti -fno-strict-aliasing -DWOMBAT',
+    }
+
+BAD_ENV = ENV + """
+This line isn't right.
+NO SPACES IN NAMES="valid value"
+"""
+
+class test_ReadEnvFile(TestCase):
+  def test_read_json(self):
+    self.assertEqual(read_env_file(JSON), RESULT)
+
+  def test_read_env(self):
+    self.assertEqual(read_env_file(ENV), RESULT)
+
+  def test_read_env_error(self):
+    errors = []
+    self.assertEqual(read_env_file(BAD_ENV, errors.append), RESULT)
+    self.assertEqual(errors, [
+        "WARNING: Didn't understand the following environment file lines:",
+        "11. >>> This line isn't right.",
+        '12. >>> NO SPACES IN NAMES="valid value"'])

python/beast/env/Tags.py

@@ -0,0 +1,17 @@
+from __future__ import absolute_import, division, print_function, unicode_literals
+
+from beast.util.Terminal import warn
+
+_TAGS = frozenset(['debug', 'optimize'])
+
+def _to_tag(name, value):
+    return '%s%s' % ('' if value else 'no', name)
+
+def get_tags(arguments, print=print):
+    result = {}
+    bad_tags = set(arguments) - _TAGS
+    if bad_tags:
+        warn("don't understand tags " + ' '.join(bad_tags), print=print)
+    debug = result.get('debug', True)
+    optimize = result.get('optimize', not debug)
+    return _to_tag('debug', debug), _to_tag('optimize', optimize)