Initial commit

LICENSE.txt

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+           DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
+                   Version 2, December 2004
+ 
+Copyright (C) 2004 Sam Hocevar <sam@hocevar.net>
+
+Everyone is permitted to copy and distribute verbatim or modified
+copies of this license document, and changing it is allowed as long
+as the name is changed.
+ 
+           DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
+  TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+ 0. You just DO WHAT THE FUCK YOU WANT TO.

README.md

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+# Scons Unity Build Generator
+
+Provides several generators for SCons to combine multiple source files into a bigger
+one to reduce compilation time, so called "unity builds". This is achieved by generating
+unity source files which in term include the actual source files and compile them using
+one of the existing SCons builders.
+
+# Usage
+
+In order to use this, just place it inside your `site_scons/site_tools` folder, enable it by
+adding "unity_build" to the tools when constructing your Environment and replace invocations
+of the Program/Library/SharedLibrary/StaticLibrary builders with their Unity... counterpart:
+
+```
+env = Environment(tools = ['default', 'unity_build'])
+
+source_files = ...
+
+env.UnityProgram(
+    target = 'my_program',
+    source = source_files,
+    ...
+)
+```
+
+The tool will generate an amount of unity source files and invoke the Program builder on these,
+forwarding any other arguments you passed.
+
+# Other Options
+
+You can control the behaviour of the builder using several Environment options:
+```
+env['UNITY_CACHE_DIR'] = '.unity' # Directory where the unity sources are stored.
+                                  # can be either a string or a Dir() node.
+env['UNITY_MAX_SOURCES'] = 15     # Maximum number of source files per unity file.
+env['UNITY_MIN_FILES'] = env.GetOption('num_jobs')
+                                  # Minimum number of unity files to generate (if possible).
+                                  # Defaults to the number of jobs passed to SCons.
+env['UNITY_DISABLE'] = False      # Set to True to completely disable unity builds. The commands
+                                  # will simply pass through their options to the regular builders.
+```

unity_build.py

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+
+import os
+import math
+from SCons.Script import *
+from SCons.Node.FS import File
+from SCons import Action
+
+"""
+Scons Unity Build Generator
+
+Provides several generators for SCons to combine multiple source files into a bigger
+one to reduce compilation time, so called "unity builds". This is achieved by generating
+unity source files which in term include the actual source files and compile them using
+one of the existing SCons builders.
+
+Usage
+-----
+In order to use this, just place it inside your `site_scons/site_tools` folder, enable it by
+adding "unity_build" to the tools when constructing your Environment and replace invocations
+of the Program/Library/SharedLibrary/StaticLibrary builders with their Unity... counterpart:
+
+env = Environment(tools = ['default', 'unity_build'])
+
+source_files = ...
+
+env.UnityProgram(
+    target = 'my_program',
+    source = source_files,
+    ...
+)
+
+The tool will generate an amount of unity source files and invoke the Program builder on these,
+forwarding any other arguments you passed.
+
+Other Options
+------------
+You can control the behaviour of the builder using several Environment options:
+env['UNITY_CACHE_DIR'] = '.unity' # Directory where the unity sources are stored.
+                                  # can be either a string or a Dir() node.
+env['UNITY_MAX_SOURCES'] = 15     # Maximum number of source files per unity file.
+env['UNITY_MIN_FILES'] = env.GetOption('num_jobs')
+                                  # Minimum number of unity files to generate (if possible).
+                                  # Defaults to the number of jobs passed to SCons.
+env['UNITY_DISABLE'] = False      # Set to True to completely disable unity builds. The commands
+                                  # will simply pass through their options to the regular builders.
+"""
+
+def exists(env : Environment):
+    return True
+
+def generate(env : Environment):
+    env.AddMethod(_make_generator(env.Program), 'UnityProgram')
+    env.AddMethod(_make_generator(env.Library), 'UnityLibrary')
+    env.AddMethod(_make_generator(env.StaticLibrary), 'UnityStaticLibrary')
+    env.AddMethod(_make_generator(env.SharedLibrary), 'UnitySharedLibrary')
+    env.SetDefault(UNITY_CACHE_DIR = '.unity')
+    env.SetDefault(UNITY_MAX_SOURCES = 15)
+    env.SetDefault(UNITY_MIN_FILES = env.GetOption('num_jobs'))
+    env.SetDefault(UNITY_DISABLE = False)
+
+def _make_generator(base_generator):
+    def generator(env, source, target, cache_dir = None, *args, **kwargs):
+        if env['UNITY_DISABLE']:
+            return base_generator(target = target, source = source, *args, **kwargs)
+        unity_source_files = []
+        source_files, other_nodes = _flatten_source(source)
+
+        max_sources_per_file = max(1, math.ceil(len(source_files) / env['UNITY_MIN_FILES']))
+        sources_per_file = min(max_sources_per_file, env['UNITY_MAX_SOURCES'])
+        
+        num_unity_files = math.ceil(len(source_files) / sources_per_file)
+
+        if not cache_dir:
+            cache_dir = env['UNITY_CACHE_DIR']
+        if not isinstance(cache_dir, str):
+            cache_dir = cache_dir.abspath
+
+        os.makedirs(cache_dir, exist_ok=True)
+        target_base_name = os.path.basename(target)
+
+        for idx in range(num_unity_files):
+            unity_filename = f'{cache_dir}/{target_base_name}_{idx}.cpp'
+            unity_source_files.append(unity_filename)
+            begin = sources_per_file*idx
+            end = sources_per_file*(idx+1)
+            _generate_unity_file(unity_filename, source_files[begin:end])
+        
+        if len(other_nodes) > 0:
+            print(f'Exluded {len(other_nodes)} node(s) from Unity build.')
+        return [base_generator(target = target, source = unity_source_files + other_nodes, *args, **kwargs)]
+    return generator
+
+def _flatten_source(source : list):
+    source_files = []
+    other_nodes = []
+    for ele in source:
+        if isinstance(ele, list):
+            more_sources, more_other = _flatten_source(ele)
+            source_files.extend(more_sources)
+            other_nodes.extend(more_other)
+        elif isinstance(ele, File):
+            source_files.append(ele.abspath)
+        elif isinstance(ele, str):
+            source_files.append(ele)
+        else:
+            print(type(ele))
+            other_nodes.append(ele)
+
+    return source_files, other_nodes
+
+def _generate_unity_file(unity_filename, sources):
+    print(f'Generating {unity_filename} from {len(sources)} source files.')
+
+    with open(unity_filename, 'w') as f:
+        for source in sources:
+            fpath = os.path.abspath(source).replace("\\", "\\\\")
+            f.write(f'#include "{fpath}"\n')