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207 lines
7.9 KiB
Python
207 lines
7.9 KiB
Python
from parso.python import tree
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from parso.python.token import PythonTokenTypes
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from parso.parser import BaseParser
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NAME = PythonTokenTypes.NAME
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INDENT = PythonTokenTypes.INDENT
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DEDENT = PythonTokenTypes.DEDENT
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class Parser(BaseParser):
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"""
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This class is used to parse a Python file, it then divides them into a
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class structure of different scopes.
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:param pgen_grammar: The grammar object of pgen2. Loaded by load_grammar.
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"""
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node_map = {
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'expr_stmt': tree.ExprStmt,
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'classdef': tree.Class,
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'funcdef': tree.Function,
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'file_input': tree.Module,
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'import_name': tree.ImportName,
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'import_from': tree.ImportFrom,
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'break_stmt': tree.KeywordStatement,
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'continue_stmt': tree.KeywordStatement,
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'return_stmt': tree.ReturnStmt,
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'raise_stmt': tree.KeywordStatement,
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'yield_expr': tree.YieldExpr,
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'del_stmt': tree.KeywordStatement,
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'pass_stmt': tree.KeywordStatement,
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'global_stmt': tree.GlobalStmt,
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'nonlocal_stmt': tree.KeywordStatement,
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'print_stmt': tree.KeywordStatement,
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'assert_stmt': tree.AssertStmt,
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'if_stmt': tree.IfStmt,
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'with_stmt': tree.WithStmt,
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'for_stmt': tree.ForStmt,
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'while_stmt': tree.WhileStmt,
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'try_stmt': tree.TryStmt,
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'sync_comp_for': tree.SyncCompFor,
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# Not sure if this is the best idea, but IMO it's the easiest way to
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# avoid extreme amounts of work around the subtle difference of 2/3
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# grammar in list comoprehensions.
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'decorator': tree.Decorator,
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'lambdef': tree.Lambda,
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'lambdef_nocond': tree.Lambda,
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'namedexpr_test': tree.NamedExpr,
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}
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default_node = tree.PythonNode
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# Names/Keywords are handled separately
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_leaf_map = {
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PythonTokenTypes.STRING: tree.String,
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PythonTokenTypes.NUMBER: tree.Number,
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PythonTokenTypes.NEWLINE: tree.Newline,
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PythonTokenTypes.ENDMARKER: tree.EndMarker,
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PythonTokenTypes.FSTRING_STRING: tree.FStringString,
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PythonTokenTypes.FSTRING_START: tree.FStringStart,
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PythonTokenTypes.FSTRING_END: tree.FStringEnd,
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}
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def __init__(self, pgen_grammar, error_recovery=True, start_nonterminal='file_input'):
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super().__init__(pgen_grammar, start_nonterminal,
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error_recovery=error_recovery)
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self.syntax_errors = []
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self._omit_dedent_list = []
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self._indent_counter = 0
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def parse(self, tokens):
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if self._error_recovery:
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if self._start_nonterminal != 'file_input':
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raise NotImplementedError
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tokens = self._recovery_tokenize(tokens)
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return super().parse(tokens)
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def convert_node(self, nonterminal, children):
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"""
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Convert raw node information to a PythonBaseNode instance.
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This is passed to the parser driver which calls it whenever a reduction of a
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grammar rule produces a new complete node, so that the tree is build
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strictly bottom-up.
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"""
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try:
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node = self.node_map[nonterminal](children)
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except KeyError:
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if nonterminal == 'suite':
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# We don't want the INDENT/DEDENT in our parser tree. Those
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# leaves are just cancer. They are virtual leaves and not real
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# ones and therefore have pseudo start/end positions and no
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# prefixes. Just ignore them.
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children = [children[0]] + children[2:-1]
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node = self.default_node(nonterminal, children)
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return node
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def convert_leaf(self, type, value, prefix, start_pos):
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# print('leaf', repr(value), token.tok_name[type])
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if type == NAME:
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if value in self._pgen_grammar.reserved_syntax_strings:
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return tree.Keyword(value, start_pos, prefix)
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else:
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return tree.Name(value, start_pos, prefix)
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return self._leaf_map.get(type, tree.Operator)(value, start_pos, prefix)
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def error_recovery(self, token):
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tos_nodes = self.stack[-1].nodes
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if tos_nodes:
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last_leaf = tos_nodes[-1].get_last_leaf()
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else:
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last_leaf = None
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if self._start_nonterminal == 'file_input' and \
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(token.type == PythonTokenTypes.ENDMARKER
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or token.type == DEDENT and not last_leaf.value.endswith('\n')
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and not last_leaf.value.endswith('\r')):
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# In Python statements need to end with a newline. But since it's
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# possible (and valid in Python) that there's no newline at the
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# end of a file, we have to recover even if the user doesn't want
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# error recovery.
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if self.stack[-1].dfa.from_rule == 'simple_stmt':
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try:
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plan = self.stack[-1].dfa.transitions[PythonTokenTypes.NEWLINE]
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except KeyError:
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pass
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else:
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if plan.next_dfa.is_final and not plan.dfa_pushes:
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# We are ignoring here that the newline would be
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# required for a simple_stmt.
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self.stack[-1].dfa = plan.next_dfa
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self._add_token(token)
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return
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if not self._error_recovery:
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return super().error_recovery(token)
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def current_suite(stack):
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# For now just discard everything that is not a suite or
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# file_input, if we detect an error.
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for until_index, stack_node in reversed(list(enumerate(stack))):
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# `suite` can sometimes be only simple_stmt, not stmt.
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if stack_node.nonterminal == 'file_input':
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break
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elif stack_node.nonterminal == 'suite':
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# In the case where we just have a newline we don't want to
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# do error recovery here. In all other cases, we want to do
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# error recovery.
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if len(stack_node.nodes) != 1:
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break
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return until_index
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until_index = current_suite(self.stack)
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if self._stack_removal(until_index + 1):
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self._add_token(token)
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else:
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typ, value, start_pos, prefix = token
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if typ == INDENT:
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# For every deleted INDENT we have to delete a DEDENT as well.
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# Otherwise the parser will get into trouble and DEDENT too early.
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self._omit_dedent_list.append(self._indent_counter)
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error_leaf = tree.PythonErrorLeaf(typ.name, value, start_pos, prefix)
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self.stack[-1].nodes.append(error_leaf)
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tos = self.stack[-1]
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if tos.nonterminal == 'suite':
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# Need at least one statement in the suite. This happend with the
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# error recovery above.
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try:
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tos.dfa = tos.dfa.arcs['stmt']
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except KeyError:
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# We're already in a final state.
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pass
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def _stack_removal(self, start_index):
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all_nodes = [node for stack_node in self.stack[start_index:] for node in stack_node.nodes]
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if all_nodes:
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node = tree.PythonErrorNode(all_nodes)
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self.stack[start_index - 1].nodes.append(node)
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self.stack[start_index:] = []
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return bool(all_nodes)
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def _recovery_tokenize(self, tokens):
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for token in tokens:
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typ = token[0]
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if typ == DEDENT:
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# We need to count indents, because if we just omit any DEDENT,
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# we might omit them in the wrong place.
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o = self._omit_dedent_list
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if o and o[-1] == self._indent_counter:
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o.pop()
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self._indent_counter -= 1
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continue
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self._indent_counter -= 1
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elif typ == INDENT:
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self._indent_counter += 1
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yield token
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