/usr/lib/falcon/parser/genparser/rules.fal is in libfalcon-engine1 0.9.6.9-git20120606-2.
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FALCON - Generic Parser
FILE: Rules.fal
Generic customizable grammar parser.
-------------------------------------------------------------------
Author: Giancarlo Niccolai
Begin: Tue, 17 Aug 2010 15:49:48 +0200
-------------------------------------------------------------------
(C) Copyright 2010: the FALCON developers (see list in AUTHORS file)
See LICENSE file for licensing details.
*/
import Regex from regex
/*# Base rule.
An abstract class.
*/
class Rule( nextState, action )
nextState = nextState
action = action
matchLen = 0
lookAhead = false
function match( text, pos )
return -1
end
function apply( context )
if self.action: self.action(context)
return self.matchLen
end
end
/*#
@brief Class representing a token rule.
Token rules are simply fixed length rules
matching the input text.
@param token the string matching a fixed token
@param action the action (function) that should be done when
hitting the token. The function will be called with
the token as last parameter.
*/
class TokenRule( token, nextState, action ) from Rule( nextState, action )
token = token
separators = " \r\n\t,.!?;:*+-/|^'\"\\#<>()[]"
function match( text, pos )
t = self.token
if (pfind = text.find( t, pos ) ) >= 0
if (pfind == 0 or self.isSep( text[(pfind-1)] )) and \
(pfind + t.len() == text.len() or self.isSep( text[(pfind + t.len())] ))
return pfind
end
end
return -1
end
function apply( ctx )
if self.action: self.action( ctx, self.token )
self.matchLen = self.lookAhead ? 0 : self.token.len()
return self.matchLen
end
function isSep( item )
return item in self.separators
end
end
/*#
Class representing a language token, with look ahead.
*/
class TokenRuleLA( token, nextState, action ) from TokenRule( token, nextState, action )
lookAhead = true
end
/*#
@brief Class representing a tag rule.
Token rules are simply fixed length rules
matching the input text.
@param token the string matching a fixed token
@param action the action (function) that should be done when
hitting the token. The function will be called with
the token as last parameter.
*/
class TagRule( tag, nextState, action ) from Rule( nextState, action )
token = tag
function match( text, pos )
t = self.token
if (pfind = text.find( t, pos ) ) >= 0
return pfind
end
return -1
end
function apply( ctx )
if self.action: self.action( ctx, self.token )
self.matchLen = self.token.len()
return self.matchLen
end
end
/*#
@brief Eats blanks
*/
class BlanksRule() from Rule( "#stay" )
matchLen = 0
function match( text, pos )
ipos = pos
l = text.len()
while pos < l
c = text[*pos]
if (c != 0x20 and c != 0x8 and c != 0x0D and c != 0x0A)
self.matchLen = pos - ipos
if self.matchLen > 0: return ipos
end
++pos
end
return -1
end
end
/*#
@brief Regular expression enabled ruler matcher.
@param token the string matching a fixed token
@param action the action (function) that should be done when
hitting the token.
The function will be called with the token as last parameter.
*/
class ReRule( re, nextState, action ) from Rule( nextState, action )
anchored = re.startsWith("^")
token = re
re = regex.Regex(re)
grabs = nil
eol = false
function match( text, pos )
// can't match "^" past the begin of the line
if self.anchored and pos > 0: return -1
re = self.re
// We need our grabs
if (rng = re.find( text, pos ))
g = []
n = 0
recapcount = re.capturedCount()
while n < recapcount
g += text[re.captured(n)]
++n
end
self.grabs = g
return rng[0]
end
return -1
end
function apply( context )
g = self.grabs
if self.action: (.[ self.action context ] + g)()
self.matchLen = g[0].len()
// allows eating EOL
if self.eol: return self.matchLen + 1
return self.matchLen
end
end
/*#
@brief Regular expression enabled ruler matcher -- consuming end of line.
@param token the string matching a fixed token
@param action the action (function) that should be done when
hitting the token.
The function will be called with the token as last parameter.
*/
class ReRuleEOL( re, nextState, action ) from ReRule( re, nextState, action )
eol = true
end
/*#
@brief Regular expression matcher with look ahead
@param token the string matching a fixed token
@param action the action (function) that should be done when
hitting the token.
The function will be called with the token as last parameter.
This rule won't indicate how many characters have been matched,
causing an application of the rule and a state change but not
discarding the matched characters.
*/
class ReRuleLA( re, nextState, action ) from ReRule( re, nextState, action )
lookAhead = true
function apply( context )
g = self.grabs
if self.action: (.[ self.action context ] + g)()
return 0
end
end
/*#
@brief Empty line rule matcher.
*/
class EmptyLineRule( nextState, action ) from Rule( nextState, action )
matchLen = 0
function match( text, pos )
if text.len() == 0: return 0
return -1
end
end
/*#
@brief Matches a single character.
*/
class CharRule( nextState, action ) from Rule( nextState, action )
grabbedChar = " "
matchLen = 1
function match( text, pos )
if text.len() > pos
self.grabbedChar = text[pos]
return pos
end
return -1
end
function apply( ctx )
if self.action: self.action( ctx, self.grabbedChar )
return 1
end
end
/*# Empty rule meant to immediately do an action and change state without consuming input. */
class DummyRule( nextState, action ) from Rule( nextState, action )
function match( text, pos )
return pos
end
end
/*# Rule matching the end of line */
class EOLRule( nextState, action ) from Rule( nextState, action )
function match( text, pos )
return text.len()
end
end
/*# Rule matching the end of line, with look ahead.
This prevents exiting from the loop checking this line when EOLRuleLA is matched
*/
class EOLRuleLA( nextState, action ) from EOLRule( nextState, action )
lookAhead = true
end
/*#
Rule combining one or more sub-rules.
@param rules An array of rules that may be matched.
@param nextState The state where to go if a sub-rule is matched.
@param actionPre An action to run as action(context, winningRule) @b before winning rule action is performed.
@param actionPost An action to run as action(context, winningRule) @b after winning rule action is performed.
If @b nextState is nil, then the winning rule state transition is applied, otherwise
@b nextstate overrides winning rule state setting.
If @b nextState contains a "*" character, it is replaced with the state from the rule. So, you can have
"#pop;*" to first pop the current state and then apply the state transition from the winner rule.
*/
class ProxyRule( rules, nextState, actionPre, actionPost) from Rule( nextState, actionPre )
rules = rules
actionPost = actionPost
winningRule = nil
hasState = nextState ? true : false
incState = "*" in nextState
origState = nextState
function match( text, pos )
self.winningRule = nil
n = 0
l = self.rules.len()
res = -1
matchPos = text.len()
while n < l
res = self.rules[n].match( text, pos )
if res == 0
// we have the winner
self.winningRule = self.rules[n]
return res
elif res > -1 and res < matchPos
matchPos = res
self.winningRule = self.rules
end
++n
end
return res
end
function apply( ctx )
if self.winningRule
if self.action: self.action( ctx, self.winningRule )
retval = self.winningRule.apply(ctx)
if self.actionPost: self.actionPost( ctx, self.winningRule )
if self.hasState
if self.incState
self.nextState = self.origState.replace( "*", self.winningRule.nextState )
end
// else, let the state it has.
else
self.nextState = self.winningRule.nextState
end
self.matchLen = retval
return retval
end
self.matchLen = 0
return 0
end
end
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