Source code for xonsh.lexer

# -*- coding: utf-8 -*-
"""Lexer for xonsh code.

Written using a hybrid of ``tokenize`` and PLY.
"""

from io import BytesIO
from keyword import kwlist

try:
    from ply.lex import LexToken
except ImportError:
    from xonsh.ply.lex import LexToken

from xonsh.platform import PYTHON_VERSION_INFO
import xonsh.tokenize as tokenize

token_map = {}
"""
Mapping from ``tokenize`` tokens (or token types) to PLY token types.  If a
simple one-to-one mapping from ``tokenize`` to PLY exists, the lexer will look
it up here and generate a single PLY token of the given type.  Otherwise, it
will fall back to handling that token using one of the handlers in
``special_handlers``.
"""

# operators
_op_map = {
    # punctuation
    ',': 'COMMA', '.': 'PERIOD', ';': 'SEMI', ':': 'COLON',
    '...': 'ELLIPSIS',
    # basic operators
    '+': 'PLUS', '-': 'MINUS', '*': 'TIMES', '@': 'AT', '/': 'DIVIDE',
    '//': 'DOUBLEDIV', '%': 'MOD', '**': 'POW', '|': 'PIPE',
    '~': 'TILDE', '^': 'XOR', '<<': 'LSHIFT', '>>': 'RSHIFT',
    '<': 'LT', '<=': 'LE', '>': 'GT', '>=': 'GE', '==': 'EQ',
    '!=': 'NE', '->': 'RARROW',
    # assignment operators
    '=': 'EQUALS', '+=': 'PLUSEQUAL', '-=': 'MINUSEQUAL',
    '*=': 'TIMESEQUAL', '@=': 'ATEQUAL', '/=': 'DIVEQUAL', '%=': 'MODEQUAL',
    '**=': 'POWEQUAL', '<<=': 'LSHIFTEQUAL', '>>=': 'RSHIFTEQUAL',
    '&=': 'AMPERSANDEQUAL', '^=': 'XOREQUAL', '|=': 'PIPEEQUAL',
    '//=': 'DOUBLEDIVEQUAL',
    # extra xonsh operators
    '?': 'QUESTION', '??': 'DOUBLE_QUESTION', '@$': 'ATDOLLAR',
    '&': 'AMPERSAND',
}
for (op, type) in _op_map.items():
    token_map[(tokenize.OP, op)] = type

token_map[tokenize.IOREDIRECT] = 'IOREDIRECT'
token_map[tokenize.STRING] = 'STRING'
token_map[tokenize.DOLLARNAME] = 'DOLLAR_NAME'
token_map[tokenize.NUMBER] = 'NUMBER'
token_map[tokenize.REGEXPATH] = 'REGEXPATH'
token_map[tokenize.NEWLINE] = 'NEWLINE'
token_map[tokenize.INDENT] = 'INDENT'
token_map[tokenize.DEDENT] = 'DEDENT'
if PYTHON_VERSION_INFO >= (3, 5, 0):
    token_map[tokenize.ASYNC] = 'ASYNC'
    token_map[tokenize.AWAIT] = 'AWAIT'


def _make_matcher_handler(tok, typ, pymode, ender):
    matcher = (')' if tok.endswith('(') else
               '}' if tok.endswith('{') else
               ']' if tok.endswith('[') else None)

    def _inner_handler(state, token):
        state['pymode'].append((pymode, tok, matcher, token.start))
        state['last'] = token
        yield _new_token(typ, tok, token.start)
    special_handlers[(tokenize.OP, tok)] = _inner_handler


[docs]def handle_name(state, token): """ Function for handling name tokens """ typ = 'NAME' state['last'] = token if state['pymode'][-1][0]: if token.string in kwlist: typ = token.string.upper() yield _new_token(typ, token.string, token.start) else: if token.string == 'and': yield _new_token('AND', token.string, token.start) elif token.string == 'or': yield _new_token('OR', token.string, token.start) else: yield _new_token('NAME', token.string, token.start)
def _end_delimiter(state, token): py = state['pymode'] s = token.string l, c = token.start if len(py) > 1: mode, orig, match, pos = py.pop() if s != match: e = '"{}" at {} ends "{}" at {} (expected "{}")' return e.format(s, (l, c), orig, pos, match) else: return 'Unmatched "{}" at line {}, column {}'.format(s, l, c)
[docs]def handle_rparen(state, token): """ Function for handling ``)`` """ e = _end_delimiter(state, token) if e is None: state['last'] = token yield _new_token('RPAREN', ')', token.start) else: yield _new_token('ERRORTOKEN', e, token.start)
[docs]def handle_rbrace(state, token): """ Function for handling ``}`` """ e = _end_delimiter(state, token) if e is None: state['last'] = token yield _new_token('RBRACE', '}', token.start) else: yield _new_token('ERRORTOKEN', e, token.start)
[docs]def handle_rbracket(state, token): """ Function for handling ``]`` """ e = _end_delimiter(state, token) if e is None: state['last'] = token yield _new_token('RBRACKET', ']', token.start) else: yield _new_token('ERRORTOKEN', e, token.start)
[docs]def handle_error_space(state, token): """ Function for handling special whitespace characters in subprocess mode """ if not state['pymode'][-1][0]: state['last'] = token yield _new_token('WS', token.string, token.start) else: yield from []
[docs]def handle_error_token(state, token): """ Function for handling error tokens """ state['last'] = token if not state['pymode'][-1][0]: typ = 'NAME' else: typ = 'ERRORTOKEN' yield _new_token(typ, token.string, token.start)
[docs]def handle_ignore(state, token): """ Function for handling tokens that should be ignored """ yield from []
[docs]def handle_double_amps(state, token): yield _new_token('AND', 'and', token.start)
[docs]def handle_double_pipe(state, token): yield _new_token('OR', 'or', token.start)
special_handlers = { tokenize.NL: handle_ignore, tokenize.COMMENT: handle_ignore, tokenize.ENCODING: handle_ignore, tokenize.ENDMARKER: handle_ignore, tokenize.NAME: handle_name, tokenize.ERRORTOKEN: handle_error_token, (tokenize.OP, ')'): handle_rparen, (tokenize.OP, '}'): handle_rbrace, (tokenize.OP, ']'): handle_rbracket, (tokenize.OP, '&&'): handle_double_amps, (tokenize.OP, '||'): handle_double_pipe, (tokenize.ERRORTOKEN, ' '): handle_error_space, } """ Mapping from ``tokenize`` tokens (or token types) to the proper function for generating PLY tokens from them. In addition to yielding PLY tokens, these functions may manipulate the Lexer's state. """ _make_matcher_handler('(', 'LPAREN', True, ')') _make_matcher_handler('[', 'LBRACKET', True, ']') _make_matcher_handler('{', 'LBRACE', True, '}') _make_matcher_handler('$(', 'DOLLAR_LPAREN', False, ')') _make_matcher_handler('$[', 'DOLLAR_LBRACKET', False, ']') _make_matcher_handler('${', 'DOLLAR_LBRACE', True, '}') _make_matcher_handler('!(', 'BANG_LPAREN', False, ')') _make_matcher_handler('![', 'BANG_LBRACKET', False, ']') _make_matcher_handler('@(', 'AT_LPAREN', True, ')') _make_matcher_handler('@$(', 'ATDOLLAR_LPAREN', False, ')')
[docs]def handle_token(state, token): """ General-purpose token handler. Makes use of ``token_map`` or ``special_map`` to yield one or more PLY tokens from the given input. Parameters ---------- state : The current state of the lexer, including information about whether we are in Python mode or subprocess mode, which changes the lexer's behavior. Also includes the stream of tokens yet to be considered. token : The token (from ``tokenize``) currently under consideration """ typ = token.type st = token.string pymode = state['pymode'][-1][0] if not pymode: if state['last'] is not None and state['last'].end != token.start: cur = token.start old = state['last'].end if cur[0] == old[0] and cur[1] > old[1]: yield _new_token('WS', token.line[old[1]:cur[1]], old) if (typ, st) in special_handlers: yield from special_handlers[(typ, st)](state, token) elif (typ, st) in token_map: state['last'] = token yield _new_token(token_map[(typ, st)], st, token.start) elif typ in special_handlers: yield from special_handlers[typ](state, token) elif typ in token_map: state['last'] = token yield _new_token(token_map[typ], st, token.start) else: m = "Unexpected token: {0}".format(token) yield _new_token("ERRORTOKEN", m, token.start)
[docs]def get_tokens(s): """ Given a string containing xonsh code, generates a stream of relevant PLY tokens using ``handle_token``. """ state = {'indents': [0], 'last': None, 'pymode': [(True, '', '', (0, 0))], 'stream': tokenize.tokenize(BytesIO(s.encode('utf-8')).readline)} while True: try: token = next(state['stream']) yield from handle_token(state, token) except StopIteration: if len(state['pymode']) > 1: pm, o, m, p = state['pymode'][-1] l, c = p e = 'Unmatched "{}" at line {}, column {}' yield _new_token('ERRORTOKEN', e.format(o, l, c), (0, 0)) break except tokenize.TokenError as e: # this is recoverable in single-line mode (from the shell) # (e.g., EOF while scanning string literal) yield _new_token('ERRORTOKEN', e.args[0], (0, 0)) break except IndentationError as e: # this is never recoverable yield _new_token('ERRORTOKEN', e, (0, 0)) break
# synthesize a new PLY token def _new_token(type, value, pos): o = LexToken() o.type = type o.value = value o.lineno, o.lexpos = pos return o
[docs]class Lexer(object): """Implements a lexer for the xonsh language.""" def __init__(self): """ Attributes ---------- fname : str Filename last : token The last token seen. lineno : int The last line number seen. """ self.fname = '' self.last = None self.beforelast = None
[docs] def build(self, **kwargs): """Part of the PLY lexer API.""" pass
[docs] def reset(self): pass
[docs] def input(self, s): """Calls the lexer on the string s.""" self.token_stream = get_tokens(s)
[docs] def token(self): """Retrieves the next token.""" self.beforelast = self.last self.last = next(self.token_stream, None) return self.last
def __iter__(self): t = self.token() while t is not None: yield t t = self.token() # # All the tokens recognized by the lexer # tokens = tuple(token_map.values()) + ( 'NAME', # name tokens 'WS', # whitespace in subprocess mode 'LPAREN', 'RPAREN', # ( ) 'LBRACKET', 'RBRACKET', # [ ] 'LBRACE', 'RBRACE', # { } 'AT_LPAREN', # @( 'BANG_LPAREN', # !( 'BANG_LBRACKET', # ![ 'DOLLAR_LPAREN', # $( 'DOLLAR_LBRACE', # ${ 'DOLLAR_LBRACKET', # $[ 'ATDOLLAR_LPAREN', # @$( ) + tuple(i.upper() for i in kwlist)