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-rw-r--r--util/newconfig/yappsrt.py172
1 files changed, 172 insertions, 0 deletions
diff --git a/util/newconfig/yappsrt.py b/util/newconfig/yappsrt.py
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+++ b/util/newconfig/yappsrt.py
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+# Yapps 2.0 Runtime
+#
+# This module is needed to run generated parsers.
+
+from string import *
+import exceptions
+import re
+
+class SyntaxError(Exception):
+ """When we run into an unexpected token, this is the exception to use"""
+ def __init__(self, pos=-1, msg="Bad Token"):
+ self.pos = pos
+ self.msg = msg
+ def __repr__(self):
+ if self.pos < 0: return "#<syntax-error>"
+ else: return "SyntaxError[@ char " + `self.pos` + ": " + self.msg + "]"
+
+class NoMoreTokens(Exception):
+ """Another exception object, for when we run out of tokens"""
+ pass
+
+class Scanner:
+ def __init__(self, patterns, ignore, input):
+ """Patterns is [(terminal,regex)...]
+ Ignore is [terminal,...];
+ Input is a string"""
+ self.tokens = []
+ self.restrictions = []
+ self.input = input
+ self.pos = 0
+ self.ignore = ignore
+ # The stored patterns are a pair (compiled regex,source
+ # regex). If the patterns variable passed in to the
+ # constructor is None, we assume that the class already has a
+ # proper .patterns list constructed
+ if patterns is not None:
+ self.patterns = []
+ for k,r in patterns:
+ self.patterns.append( (k, re.compile(r)) )
+
+ def token(self, i, restrict=0):
+ """Get the i'th token, and if i is one past the end, then scan
+ for another token; restrict is a list of tokens that
+ are allowed, or 0 for any token."""
+ if i == len(self.tokens): self.scan(restrict)
+ if i < len(self.tokens):
+ # Make sure the restriction is more restricted
+ if restrict and self.restrictions[i]:
+ for r in restrict:
+ if r not in self.restrictions[i]:
+ raise "Unimplemented: restriction set changed"
+ return self.tokens[i]
+ raise NoMoreTokens()
+
+ def __repr__(self):
+ """Print the last 10 tokens that have been scanned in"""
+ output = ''
+ for t in self.tokens[-10:]:
+ output = '%s\n (@%s) %s = %s' % (output,t[0],t[2],`t[3]`)
+ return output
+
+ def scan(self, restrict):
+ """Should scan another token and add it to the list, self.tokens,
+ and add the restriction to self.restrictions"""
+ # Keep looking for a token, ignoring any in self.ignore
+ while 1:
+ # Search the patterns for the longest match, with earlier
+ # tokens in the list having preference
+ best_match = -1
+ best_pat = '(error)'
+ for p, regexp in self.patterns:
+ # First check to see if we're ignoring this token
+ if restrict and p not in restrict and p not in self.ignore:
+ continue
+ m = regexp.match(self.input, self.pos)
+ if m and len(m.group(0)) > best_match:
+ # We got a match that's better than the previous one
+ best_pat = p
+ best_match = len(m.group(0))
+
+ # If we didn't find anything, raise an error
+ if best_pat == '(error)' and best_match < 0:
+ msg = "Bad Token"
+ if restrict:
+ msg = "Trying to find one of "+join(restrict,", ")
+ raise SyntaxError(self.pos, msg)
+
+ # If we found something that isn't to be ignored, return it
+ if best_pat not in self.ignore:
+ # Create a token with this data
+ token = (self.pos, self.pos+best_match, best_pat,
+ self.input[self.pos:self.pos+best_match])
+ self.pos = self.pos + best_match
+ # Only add this token if it's not in the list
+ # (to prevent looping)
+ if not self.tokens or token != self.tokens[-1]:
+ self.tokens.append(token)
+ self.restrictions.append(restrict)
+ return
+ else:
+ # This token should be ignored ..
+ self.pos = self.pos + best_match
+
+class Parser:
+ def __init__(self, scanner):
+ self._scanner = scanner
+ self._pos = 0
+
+ def _peek(self, *types):
+ """Returns the token type for lookahead; if there are any args
+ then the list of args is the set of token types to allow"""
+ tok = self._scanner.token(self._pos, types)
+ return tok[2]
+
+ def _scan(self, type):
+ """Returns the matched text, and moves to the next token"""
+ tok = self._scanner.token(self._pos, [type])
+ if tok[2] != type:
+ raise SyntaxError(tok[0], 'Trying to find '+type)
+ self._pos = 1+self._pos
+ return tok[3]
+
+
+
+def print_error(input, err, scanner):
+ """This is a really dumb long function to print error messages nicely."""
+ p = err.pos
+ # Figure out the line number
+ line = count(input[:p], '\n')
+ print err.msg+" on line "+`line+1`+":"
+ # Now try printing part of the line
+ text = input[max(p-80,0):p+80]
+ p = p - max(p-80,0)
+
+ # Strip to the left
+ i = rfind(text[:p],'\n')
+ j = rfind(text[:p],'\r')
+ if i < 0 or (j < i and j >= 0): i = j
+ if i >= 0 and i < p:
+ p = p - i - 1
+ text = text[i+1:]
+
+ # Strip to the right
+ i = find(text,'\n',p)
+ j = find(text,'\r',p)
+ if i < 0 or (j < i and j >= 0): i = j
+ if i >= 0:
+ text = text[:i]
+
+ # Now shorten the text
+ while len(text) > 70 and p > 60:
+ # Cut off 10 chars
+ text = "..." + text[10:]
+ p = p - 7
+
+ # Now print the string, along with an indicator
+ print '> ',text
+ print '> ',' '*p + '^'
+ print 'List of nearby tokens:', scanner
+
+def wrap_error_reporter(parser, rule):
+ try: return getattr(parser, rule)()
+ except SyntaxError, s:
+ input = parser._scanner.input
+ try:
+ print_error(input, s, parser._scanner)
+ except ImportError:
+ print 'Syntax Error',s.msg,'on line',1+count(input[:s.pos], '\n')
+ except NoMoreTokens:
+ print 'Could not complete parsing; stopped around here:'
+ print parser._scanner
+