def _compile_rule_chunk(self, chunk_id):
# Loop through all known rule names, and if they are defined within
# this grammar create a rule definition entry.
definitions = []
for name, id in zip(self._rules,
xrange(1, len(self._rules) + 1)):
# Skip imported rules.
if name in self._import_rules:
if name in self._rule_definitions:
raise CompilerError("Rule '%s' cannot be both imported" \
" and defined in a grammar" % name)
continue
# Make sure that a definition has been given.
if name not in self._rule_definitions:
raise CompilerError("Rule '%s' is neither imported" \
" nor defined" % name)
# Build the definition sequence for this rule.
elements = []
for t, v in self._rule_definitions[name]:
# Definition element:
# - wType; start:1, end:2, word:3, rule:4, list:6
# - wProb; probability rating, use 0.
# - dwValue; depends on wType as follows:
# - if wType is start or end, then dwValue is one of
# sequence:1, alternative:2, repetition:3, optional:4
# - if wType is word, rule, or list, then dwValue is
# the ID of the corresponding element.
element = struct.pack("HHL", t, 0, v)
elements.append(element)
# Definition header:
# - dwSize; size of this rule definition in bytes including
# this header.
# - dwNum; the ID of this rule.
definition_size = 8 + sum([len(s) for s in elements])
definition = struct.pack("LL", definition_size, id)
definition += "".join(elements)
definitions.append(definition)
# Concatenate all the rule definitions.
definition_data = "".join(definitions)
# Rule definition chunk header:
# - dwChunkId; rule definitions:3
# - dwChunkSize; size of this chunk in bytes excluding this header.
header = struct.pack("LL", chunk_id, len(definition_data))
# Return the header and the rule definitions.
return header + definition_data
def end_optional(self):
"""End a optional structure in the rule currently being defined."""
# Make sure a rule is being defined at the moment.
if not self._current_rule_name:
raise CompilerError("Cannot end a optional because" \
" no rule is currently being defined.")
# Append the end-tag.
self._current_rule_definition.append(
(self._end_type, self._opt_value) )
def start_repetition(self):
"""start a repetition structure in the rule currently being defined."""
# Make sure a rule is being defined at the moment.
if not self._current_rule_name:
raise CompilerError("Cannot start a repetition because" \
" no rule is currently being defined.")
# Append the start-tag.
self._current_rule_definition.append(
(self._start_type, self._rep_value) )
def start_rule_definition(self, name, exported=False):
"""start defining a rule."""
# Make sure no rule is being defined at the moment.
if self._current_rule_name:
raise CompilerError("Cannot start defining a rule while" \
"a different rule is already being defined.")
assert isinstance(name, str), "The rule name must be a string."
self._current_rule_name = name
self._current_rule_export = exported
self._current_rule_definition = []
def _compile_rule_ref(self, element, src_state, dst_state, grammar,
grammar_handle):
rule_handle = grammar_handle.Rules.FindRule(element.rule.name)
if not rule_handle:
grammar.add_rule(element.rule)
self._compile_rule(element.rule, grammar, grammar_handle)
rule_handle = grammar_handle.Rules.FindRule(element.rule.name)
if not rule_handle:
raise CompilerError(
"%s: Failed to create rule dependency: %r." %
(self, element.rule.name))
src_state.AddRuleTransition(dst_state, rule_handle)
def add_rule(self, rule, imported = False):
"""Append a rule reference to the rule currently being defined."""
# Make sure a rule is being defined at the moment.
if not self._current_rule_name:
raise CompilerError("Cannot add rule '%s' because" \
" no rule is currently being defined." % rule)
# Determine this rule's ID. If this rule has not been used before,
# register it.
if rule not in self._rules:
self._rules.append(rule)
if imported: self._import_rules.append(rule)
id = len(self._rules)
# If this rule has been referenced multiple times, make sure that
# it has either always being imported or never been imported.
elif imported != (rule in self._import_rules):
raise CompilerError("Rule '%s' cannot be referenced as both" \
" imported and not imported within a" \
" grammar." % rule)
else:
id = self._rules.index(rule) + 1
# Append the rule to the rule currently being defined.
self._current_rule_definition.append( (self._rule_type, id) )
def add_list(self, list):
"""Append a list to the rule currently being defined."""
# Make sure a rule is being defined at the moment.
if not self._current_rule_name:
raise CompilerError("Cannot add list '%s' because" \
" no rule is currently being defined." % list)
# Determine this list's ID. If this list has not been used before,
# register it.
if list not in self._lists:
self._lists.append(list)
id = len(self._lists)
else:
id = self._lists.index(list) + 1
# Append the list to the rule currently being defined.
self._current_rule_definition.append( (self._list_type, id) )
def add_word(self, word):
"""Append a literal word to the rule currently being defined."""
# Make sure a rule is being defined at the moment.
if not self._current_rule_name:
raise CompilerError("Cannot add word '%s' because" \
" no rule is currently being defined." % word)
# Determine this word's ID. If this word has not been used before,
# register it.
if word not in self._words:
self._words.append(word)
id = len(self._words)
else:
id = self._words.index(word) + 1
# Append the word to the rule currently being defined.
self._current_rule_definition.append( (self._word_type, id) )
def end_rule_definition(self):
"""End defining a rule."""
# Make sure a rule is being defined at the moment.
if not self._current_rule_name:
raise CompilerError("Cannot end defining a rule when" \
" no rule is being defined.")
# Make sure that no other rule has been defined with this name.
if self._current_rule_name in self._rule_definitions:
raise CompilerError("Rule '%s' defined more than once." % \
self._current_rule_name)
# If this rule has not been used before, register it.
if self._current_rule_name not in self._rules:
self._rules.append(self._current_rule_name)
if self._current_rule_export:
self._export_rules.append(self._current_rule_name)
self._rule_definitions[self._current_rule_name] = \
self._current_rule_definition
self._current_rule_name = None
self._current_rule_export = None
self._current_rule_definition = None
def compile(self):
"""Compile a binary grammar of this compiler's current state."""
# Make sure no rule is being defined at the moment.
if self._current_rule_name:
raise CompilerError("Cannot compile grammar while a rule" \
" is being defined.")
# Grammar header:
# - dwType; use 0.
# - dwFlags; use 0.
output = [struct.pack("LL", 0, 0)]
# Lists of the names and IDs of exports, imports, lists, and words.
output.append(self._compile_id_chunk(4, self._export_rules, self._rules))
output.append(self._compile_id_chunk(5, self._import_rules, self._rules))
output.append(self._compile_id_chunk(6, self._lists, self._lists))
output.append(self._compile_id_chunk(2, self._words, self._words))
# List of rule definitions.
output.append(self._compile_rule_chunk(3))
# Return a concatenation of the header and chunks.
return "".join(output)
