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Diffstat (limited to 'cmd2/parsing.py')
| -rw-r--r-- | cmd2/parsing.py | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/cmd2/parsing.py b/cmd2/parsing.py new file mode 100644 index 00000000..41a3ed0b --- /dev/null +++ b/cmd2/parsing.py @@ -0,0 +1,212 @@ +# +# -*- coding: utf-8 -*- +"""Command parsing classes for cmd2""" + +import re +import shlex + +import cmd2 + +class Command(): + """Store the results of a parsed command.""" + pass + +class CommandParser(): + """Parse raw text into command components.""" + def __init__( + self, + quotes=['"', "'"], + allow_redirection=True, + redirection_chars=['|', '<', '>'], + terminators=[';'], + multilineCommands = [], + ): + self.quotes = quotes + self.allow_redirection = allow_redirection + self.redirection_chars = redirection_chars + self.terminators = terminators + self.multilineCommands = multilineCommands + + def parseString(self, rawinput): + result = Command() + result.raw = rawinput + result.command = None + result.multilineCommand = None + result.args = None + result.terminator = None + result.suffix = None + result.pipeTo = None + result.output = None + result.outputTo = None + + # strip C-style and C++-style comments + # shlex will handle the python/shell style comments for us + def replacer(match): + s = match.group(0) + if s.startswith('/'): + # treat the removed comment as an empty string + return '' + else: + return s + pattern = re.compile( + r'//.*?$|/\*.*?\*/|\'(?:\\.|[^\\\'])*\'|"(?:\\.|[^\\"])*"', + re.DOTALL | re.MULTILINE + ) + rawinput = re.sub(pattern, replacer, rawinput) + + s = shlex.shlex(rawinput, posix=False) + s.whitespace_split = True + tokens = self.split_on_punctuation(list(s)) + + # of the valid terminators, find the first one to occur in the input + terminator_pos = len(tokens)+1 + terminator = None + for test_terminator in self.terminators: + try: + pos = tokens.index(test_terminator) + if pos < terminator_pos: + terminator_pos = pos + terminator = test_terminator + except ValueError: + # the terminator is not in the tokens + pass + + if terminator: + terminator_pos = tokens.index(terminator) + # everything before the first terminator is the command and the args + (result.command, result.args) = self._command_and_args(tokens[:terminator_pos]) + result.terminator = tokens[terminator_pos] + # we will set the suffix later + # remove all the tokens before and including the terminator + tokens = tokens[terminator_pos+1:] + + # check for input from file + try: + if tokens[0] == '<': + result.inputFrom = ' '.join(tokens[1:]) + tokens = [] + except IndexError: + # no input from file + pass + + # check for output redirect + try: + output_pos = tokens.index('>') + result.output = '>' + result.outputTo = ' '.join(tokens[output_pos+1:]) + # remove all the tokens after the output redirect + tokens = tokens[:output_pos] + except ValueError: + pass + + # check for paste buffer + try: + output_pos = tokens.index('>>') + result.output = '>>' + # remove all tokens after the output redirect + tokens = tokens[:output_pos] + except ValueError: + pass + + # check for pipes + try: + # find the first pipe if it exists + pipe_pos = tokens.index('|') + # set everything after the first pipe to result.pipeTo + result.pipeTo = ' '.join(tokens[pipe_pos+1:]) + # remove all the tokens after the pipe + tokens = tokens[:pipe_pos] + except ValueError: + # no pipe in the tokens + pass + + if result.terminator: + # whatever is left is the suffix + result.suffix = ' '.join(tokens) + else: + # no terminator, so whatever is left is the command and the args + (result.command, result.args) = self._command_and_args(tokens) + + if result.command in self.multilineCommands: + result.multilineCommand = result.command + + return result + + def _command_and_args(self, tokens): + """given a list of tokens, and return a tuple of the command + and the args as a string. + """ + command = None + args = None + + if tokens: + command = tokens[0] + + if len(tokens) > 1: + args = ' '.join(tokens[1:]) + + return (command, args) + + def split_on_punctuation(self, initial_tokens): + """ + # Further splits tokens from a command line using punctuation characters + # as word breaks when they are in unquoted strings. Each run of punctuation + # characters is treated as a single token. + + :param initial_tokens: the tokens as parsed by shlex + :return: the punctuated tokens + """ + punctuation = [] + punctuation.extend(self.terminators) + if self.allow_redirection: + punctuation.extend(self.redirection_chars) + + punctuated_tokens = [] + + for cur_initial_token in initial_tokens: + + # Save tokens up to 1 character in length or quoted tokens. No need to parse these. + if len(cur_initial_token) <= 1 or cur_initial_token[0] in self.quotes: + punctuated_tokens.append(cur_initial_token) + continue + + # Iterate over each character in this token + cur_index = 0 + cur_char = cur_initial_token[cur_index] + + # Keep track of the token we are building + new_token = '' + + while True: + if cur_char not in punctuation: + + # Keep appending to new_token until we hit a punctuation char + while cur_char not in punctuation: + new_token += cur_char + cur_index += 1 + if cur_index < len(cur_initial_token): + cur_char = cur_initial_token[cur_index] + else: + break + + else: + cur_punc = cur_char + + # Keep appending to new_token until we hit something other than cur_punc + while cur_char == cur_punc: + new_token += cur_char + cur_index += 1 + if cur_index < len(cur_initial_token): + cur_char = cur_initial_token[cur_index] + else: + break + + # Save the new token + punctuated_tokens.append(new_token) + new_token = '' + + # Check if we've viewed all characters + if cur_index >= len(cur_initial_token): + break + + return punctuated_tokens |