project.py: Support project options

  o Load the option definitions with the OptionPool

  o Set the user selected project option values according to the passed Context

  o Process conditionals in the loaded project configuration,
    excepting for the project name and actual option definitions

  o Removed a lot of examples from the default config.

    This is getting moved into more structured documentation, and the
    default config is only presented to the user beside the documentation
    which describes what each thing means.

2 files changed, 47 insertions, 142 deletions

diff --git a/buildstream/data/projectconfig.yaml b/buildstream/data/projectconfig.yaml
index 2e47aa87b..aca021618 100644
--- a/buildstream/data/projectconfig.yaml
+++ b/buildstream/data/projectconfig.yaml
@@ -1,70 +1,8 @@
 # Default BuildStream project configuration.
 
-# Project name
-#
-# name: myproject
-
-# Format version requirements
-#
-# Indicates the minimum required format version the
-# project requires.
-#
-required-versions:
-
-  # The minimum base BuildStream format
-  project: 0
-
-  # A minimum plugin format version for each individual
-  # plugin (as advertized by the plugin BST_FORMAT_VERSION
-  # class attributes), may be asserted here.
-  #
-  # E.g., to require version 3 of the the autotools
-  # element format:
-  #
-  #   elements:
-  #     autotools: 3
-  #
-  elements: {}
-  sources: {}
-
-# Base project relative element path, elements will be loaded
-# from this base.
-
-element-path: .
-
-# Alias configuration
-#
-# Aliases are entirely project specific, they are
-# configured as a simple dictionary, example:
-#
-# aliases:
-#   baserock: git://git.baserock.org/baserock/
-#   freedesktop: git://anongit.freedesktop.org/
-
-
-# Plugin path configuration
-#
-# You may specify one or more project relative paths to
-# subdirectories where plugins should be loaded from.
-#
-# plugins:
-#
-#   elements:
-#   - plugins/local-elements
-#   - plugins/shared-elements
-#
-#   sources:
-#   - plugins/local-sources
-
 
 # Variable Configuration
 #
-# You may override the defaults of variables on a project wide
-# basis by specifying the 'variables' attribute.
-#
-# The defaults for this version of buildstream are listed
-# below.
-#
 variables:
 
   # Maximum number of parallel build processes within a given
@@ -147,18 +85,6 @@ environment-nocache: []
 # Defaults for the 'split-rules' public data found on elements
 # in the 'bst' domain.
 #
-# These define patterns for categorizing the output of build
-# elements so that selective composition can be performed by
-# plugins later on.
-#
-# Elements may extend these rules by adding entries to the
-# various split domains either in a plugin definition or
-# in a project element declaration.
-#
-# Note that the split rules reported by
-# Element.get_public_data('bst') will have any variables for
-# the given element already expanded.
-#
 split-rules:
 
   # The runtime domain includes whatever is needed for the
@@ -233,41 +159,3 @@ split-rules:
     %{datadir}/zoneinfo
   - |
     %{datadir}/zoneinfo/**
-
-#
-#    Artifacts
-#
-artifacts:
-
-  # A url from which to download prebuilt artifacts
-  pull-url: ''
-
-  # A url to upload built artifacts to
-  # (must point to the same repository as pull-url)
-  push-url: ''
-
-  # Specify the port number for pushing artifacts, if it's
-  # not the default port 22
-  push-port: 22
-
-# Element Overrides
-#
-# Base attributes declared by element default yaml files
-# can be overridden on a project wide basis. The elements
-# dictionary can be used to override variables, environments
-# or plugin specific configuration data as shown below.
-#
-#
-# elements:
-#
-#   autotools:
-#
-#     variables:
-#       bindir: "%{prefix}/bin"
-#
-#     config:
-#       configure-commands: ...
-#
-#     environment:
-#       PKG_CONFIG_PATH=%{libdir}/pkgconfig
-#
diff --git a/buildstream/project.py b/buildstream/project.py
index dcf1c1e1f..d3d8dc525 100644
--- a/buildstream/project.py
+++ b/buildstream/project.py
@@ -37,6 +37,7 @@ from . import _yaml
 from . import _loader  # For resolve_arch()
 from ._profile import Topics, profile_start, profile_end
 from . import LoadError, LoadErrorReason
+from ._options import OptionPool
 
 BST_FORMAT_VERSION = 0
 """The base BuildStream format version
@@ -60,17 +61,11 @@ _ALIAS_SEPARATOR = ':'
 
 
 class Project():
-    """Project Configuration
+    """Project()
 
-    Args:
-       directory (str): The project directory
-       host_arch (str): Symbolic host machine architecture name
-       target_arch (str): Symbolic target machine architecture name
-
-    Raises:
-       :class:`.LoadError`
+    The Project Configuration
     """
-    def __init__(self, directory, host_arch, target_arch=None):
+    def __init__(self, directory, context):
 
         self.name = None
         """str: The project name"""
@@ -81,16 +76,16 @@ class Project():
         self.element_path = None
         """str: Absolute path to where elements are loaded from within the project"""
 
-        self._variables = {}    # The default variables overridden with project wide overrides
-        self._environment = {}  # The base sandbox environment
-        self._elements = {}     # Element specific configurations
-        self._aliases = {}      # Aliases dictionary
-        self._workspaces = {}   # Workspaces
+        self._context = context  # The invocation Context
+        self._variables = {}     # The default variables overridden with project wide overrides
+        self._environment = {}   # The base sandbox environment
+        self._elements = {}      # Element specific configurations
+        self._aliases = {}       # Aliases dictionary
+        self._workspaces = {}    # Workspaces
         self._plugin_source_paths = []   # Paths to custom sources
         self._plugin_element_paths = []  # Paths to custom plugins
+        self._options = None    # Project options, the OptionPool
         self._cache_key = None
-        self._host_arch = host_arch
-        self._target_arch = target_arch or host_arch
         self._source_format_versions = {}
         self._element_format_versions = {}
 
@@ -137,12 +132,12 @@ class Project():
         variables = _yaml.node_get(config, Mapping, 'variables')
         variables['max-jobs'] = multiprocessing.cpu_count()
 
-        variables['bst-host-arch'] = self._host_arch
-        variables['bst-target-arch'] = self._target_arch
+        variables['bst-host-arch'] = self._context.host_arch
+        variables['bst-target-arch'] = self._context.target_arch
 
         # This is kept around for compatibility with existing definitions,
         # but we should probably remove it due to being ambiguous.
-        variables['bst-arch'] = self._host_arch
+        variables['bst-arch'] = self._context.host_arch
 
         # Load project local config and override the builtin
         project_conf = _yaml.load(projectfile)
@@ -154,25 +149,47 @@ class Project():
             'split-rules', 'elements', 'plugins',
             'aliases', 'name',
             'arches', 'host-arches',
-            'artifacts',
+            'artifacts', 'options',
         ])
 
+        # The project name, element path and option declarations
+        # are constant and cannot be overridden by option conditional statements
+        self.name = _yaml.node_get(config, str, 'name')
+        self.element_path = os.path.join(
+            self.directory,
+            _yaml.node_get(config, str, 'element-path', default_value='.')
+        )
+
+        # Load project options
+        options_node = _yaml.node_get(config, Mapping, 'options', default_value={})
+        self._options = OptionPool(self.element_path)
+        self._options.load(options_node)
+
+        # Collect option values specified in the user configuration
+        overrides = self._context._get_overrides(self.name)
+        override_options = _yaml.node_get(overrides, Mapping, 'options', default_value={})
+        self._options.load_values(override_options, self._context._cli_options)
+
+        # We're done modifying options, now we can use them for substitutions
+        self._options.resolve()
+
+        #
+        # Now resolve any conditionals in the remaining configuration,
+        # any conditionals specified for project option declarations,
+        # or conditionally specifying the project name; will be ignored.
+        #
+        self._options.process_node(config)
+
         # Resolve arches keyword, project may have arch conditionals
-        _loader.resolve_arch(config, self._host_arch, self._target_arch)
+        _loader.resolve_arch(config, self._context.host_arch, self._context.target_arch)
 
         #
         # Now all YAML composition is done, from here on we just load
         # the values from our loaded configuration dictionary.
         #
 
-        self.name = _yaml.node_get(config, str, 'name')
-        self.element_path = os.path.join(
-            self.directory,
-            _yaml.node_get(config, str, 'element-path')
-        )
-
         # Load artifacts pull/push configuration for this project
-        artifacts = _yaml.node_get(config, Mapping, 'artifacts')
+        artifacts = _yaml.node_get(config, Mapping, 'artifacts', default_value={})
         _yaml.node_validate(artifacts, ['pull-url', 'push-url', 'push-port'])
         self.artifact_pull = _yaml.node_get(artifacts, str, 'pull-url', default_value='') or None
         self.artifact_push = _yaml.node_get(artifacts, str, 'push-url', default_value='') or None
@@ -182,11 +199,11 @@ class Project():
         self._workspaces = self._load_workspace_config()
 
         # Version requirements
-        versions = _yaml.node_get(config, Mapping, 'required-versions')
+        versions = _yaml.node_get(config, Mapping, 'required-versions', default_value={})
         _yaml.node_validate(versions, ['project', 'elements', 'sources'])
 
         # Assert project version first
-        format_version = _yaml.node_get(versions, int, 'project')
+        format_version = _yaml.node_get(versions, int, 'project', default_value=0)
         if BST_FORMAT_VERSION < format_version:
             major, minor = utils.get_bst_version()
             raise LoadError(