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# xpath.tcl --
#
# Provides an XPath parser for Tcl,
# plus various support procedures
#
# Copyright (c) 2000-2003 Zveno Pty Ltd
#
# See the file "LICENSE" in this distribution for information on usage and
# redistribution of this file, and for a DISCLAIMER OF ALL WARRANTIES.
#
# $Id: xpath.tcl,v 1.1.1.1 2009/01/16 22:11:49 joye Exp $
package provide xpath 1.0
# We need the XML package for definition of Names
package require xml
namespace eval xpath {
namespace export split join createnode
variable axes {
ancestor
ancestor-or-self
attribute
child
descendant
descendant-or-self
following
following-sibling
namespace
parent
preceding
preceding-sibling
self
}
variable nodeTypes {
comment
text
processing-instruction
node
}
# NB. QName has parens for prefix
variable nodetestExpr ^(${::xml::QName})${::xml::allWsp}(\\(${::xml::allWsp}(("|')(.*?)\\5)?${::xml::allWsp}\\))?${::xml::allWsp}(.*)
variable nodetestExpr2 ((($::xml::QName)${::xml::allWsp}(\\(${::xml::allWsp}(("|')(.*?)\\7)?${::xml::allWsp}\\))?)|${::xml::allWsp}(\\*))${::xml::allWsp}(.*)
}
# xpath::split --
#
# Parse an XPath location path
#
# Arguments:
# locpath location path
#
# Results:
# A Tcl list representing the location path.
# The list has the form: {{axis node-test {predicate predicate ...}} ...}
# Where each list item is a location step.
proc xpath::split locpath {
set leftover {}
set result [InnerSplit $locpath leftover]
if {[string length [string trim $leftover]]} {
return -code error "unexpected text \"$leftover\""
}
return $result
}
proc xpath::InnerSplit {locpath leftoverVar} {
upvar $leftoverVar leftover
variable axes
variable nodetestExpr
variable nodetestExpr2
# First determine whether we have an absolute location path
if {[regexp {^/(.*)} $locpath discard locpath]} {
set path {{}}
} else {
set path {}
}
while {[string length [string trimleft $locpath]]} {
if {[regexp {^\.\.(.*)} $locpath discard locpath]} {
# .. abbreviation
set axis parent
set nodetest *
} elseif {[regexp {^/(.*)} $locpath discard locpath]} {
# // abbreviation
set axis descendant-or-self
if {[regexp ^$nodetestExpr2 [string trimleft $locpath] discard discard discard nodetest discard typetest discard discard literal wildcard locpath]} {
set nodetest [ResolveWildcard $nodetest $typetest $wildcard $literal]
} else {
set leftover $locpath
return $path
}
} elseif {[regexp ^\\.${::xml::allWsp}(.*) $locpath discard locpath]} {
# . abbreviation
set axis self
set nodetest *
} elseif {[regexp ^@($::xml::QName)${::xml::allWsp}=${::xml::allWsp}"(\[^"\])"(.*) $locpath discard attrName discard attrValue locpath]} {
# @ abbreviation
set axis attribute
set nodetest $attrName
} elseif {[regexp ^@($::xml::QName)${::xml::allWsp}=${::xml::allWsp}'(\[^'\])'(.*) $locpath discard attrName discard attrValue locpath]} {
# @ abbreviation
set axis attribute
set nodetest $attrName
} elseif {[regexp ^@($::xml::QName)(.*) $locpath discard attrName discard2 locpath]} {
# @ abbreviation
set axis attribute
set nodetest $attrName
} elseif {[regexp ^((${::xml::QName})${::xml::allWsp}::${::xml::allWsp})?\\*(.*) $locpath discard discard axis discard locpath]} {
# wildcard specified
set nodetest *
if {![string length $axis]} {
set axis child
}
} elseif {[regexp ^((${::xml::QName})${::xml::allWsp}::${::xml::allWsp})?$nodetestExpr2 $locpath discard discard axis discard discard discard nodetest discard typetest discard discard literal wildcard locpath]} {
# nodetest, with or without axis
if {![string length $axis]} {
set axis child
}
set nodetest [ResolveWildcard $nodetest $typetest $wildcard $literal]
} else {
set leftover $locpath
return $path
}
# ParsePredicates
set predicates {}
set locpath [string trimleft $locpath]
while {[regexp {^\[(.*)} $locpath discard locpath]} {
if {[regexp {^([0-9]+)(\].*)} [string trim $locpath] discard posn locpath]} {
set predicate [list = {function position {}} [list number $posn]]
} else {
set leftover2 {}
set predicate [ParseExpr $locpath leftover2]
set locpath $leftover2
unset leftover2
}
if {[regexp {^\](.*)} [string trimleft $locpath] discard locpath]} {
lappend predicates $predicate
} else {
return -code error "unexpected text in predicate \"$locpath\""
}
}
set axis [string trim $axis]
set nodetest [string trim $nodetest]
# This step completed
if {[lsearch $axes $axis] < 0} {
return -code error "invalid axis \"$axis\""
}
lappend path [list $axis $nodetest $predicates]
# Move to next step
if {[string length $locpath] && ![regexp ^/(.*) $locpath discard locpath]} {
set leftover $locpath
return $path
}
}
return $path
}
# xpath::ParseExpr --
#
# Parse one expression in a predicate
#
# Arguments:
# locpath location path to parse
# leftoverVar Name of variable in which to store remaining path
#
# Results:
# Returns parsed expression as a Tcl list
proc xpath::ParseExpr {locpath leftoverVar} {
upvar $leftoverVar leftover
variable nodeTypes
set expr {}
set mode expr
set stack {}
while {[string index [string trimleft $locpath] 0] != "\]"} {
set locpath [string trimleft $locpath]
switch $mode {
expr {
# We're looking for a term
if {[regexp ^-(.*) $locpath discard locpath]} {
# UnaryExpr
lappend stack "-"
} elseif {[regexp ^\\\$({$::xml::QName})(.*) $locpath discard varname discard locpath]} {
# VariableReference
lappend stack [list varRef $varname]
set mode term
} elseif {[regexp {^\((.*)} $locpath discard locpath]} {
# Start grouping
set leftover2 {}
lappend stack [list group [ParseExpr $locpath leftover2]]
set locpath $leftover2
unset leftover2
if {[regexp {^\)(.*)} [string trimleft $locpath] discard locpath]} {
set mode term
} else {
return -code error "unexpected text \"$locpath\", expected \")\""
}
} elseif {[regexp {^"([^"]*)"(.*)} $locpath discard literal locpath]} {
# Literal (" delimited)
lappend stack [list literal $literal]
set mode term
} elseif {[regexp {^'([^']*)'(.*)} $locpath discard literal locpath]} {
# Literal (' delimited)
lappend stack [list literal $literal]
set mode term
} elseif {[regexp {^([0-9]+(\.[0-9]+)?)(.*)} $locpath discard number discard locpath]} {
# Number
lappend stack [list number $number]
set mode term
} elseif {[regexp {^(\.[0-9]+)(.*)} $locpath discard number locpath]} {
# Number
lappend stack [list number $number]
set mode term
} elseif {[regexp ^(${::xml::QName})\\(${::xml::allWsp}(.*) $locpath discard functionName discard locpath]} {
# Function call start or abbreviated node-type test
if {[lsearch $nodeTypes $functionName] >= 0} {
# Looking like a node-type test
if {[regexp ^\\)${::xml::allWsp}(.*) $locpath discard locpath]} {
lappend stack [list path [list child [list $functionName ()] {}]]
set mode term
} else {
return -code error "invalid node-type test \"$functionName\""
}
} else {
if {[regexp ^\\)${::xml::allWsp}(.*) $locpath discard locpath]} {
set parameters {}
} else {
set leftover2 {}
set parameters [ParseExpr $locpath leftover2]
set locpath $leftover2
unset leftover2
while {[regexp {^,(.*)} $locpath discard locpath]} {
set leftover2 {}
lappend parameters [ParseExpr $locpath leftover2]
set locpath $leftover2
unset leftover2
}
if {![regexp ^\\)${::xml::allWsp}(.*) [string trimleft $locpath] discard locpath]} {
return -code error "unexpected text \"locpath\" - expected \")\""
}
}
lappend stack [list function $functionName $parameters]
set mode term
}
} else {
# LocationPath
set leftover2 {}
lappend stack [list path [InnerSplit $locpath leftover2]]
set locpath $leftover2
unset leftover2
set mode term
}
}
term {
# We're looking for an expression operator
if {[regexp ^-(.*) $locpath discard locpath]} {
# UnaryExpr
set stack [linsert $stack 0 expr "-"]
set mode expr
} elseif {[regexp ^(and|or|\\=|!\\=|<|>|<\\=|>\\=|\\||\\+|\\-|\\*|div|mod)(.*) $locpath discard exprtype locpath]} {
# AndExpr, OrExpr, EqualityExpr, RelationalExpr or UnionExpr
set stack [linsert $stack 0 $exprtype]
set mode expr
} else {
return -code error "unexpected text \"$locpath\", expecting operator"
}
}
default {
# Should never be here!
return -code error "internal error"
}
}
}
set leftover $locpath
return $stack
}
# xpath::ResolveWildcard --
proc xpath::ResolveWildcard {nodetest typetest wildcard literal} {
variable nodeTypes
switch -glob -- [string length $nodetest],[string length $typetest],[string length $wildcard],[string length $literal] {
0,0,0,* {
return -code error "bad location step (nothing parsed)"
}
0,0,* {
# Name wildcard specified
return *
}
*,0,0,* {
# Element type test - nothing to do
return $nodetest
}
*,0,*,* {
# Internal error?
return -code error "bad location step (found both nodetest and wildcard)"
}
*,*,0,0 {
# Node type test
if {[lsearch $nodeTypes $nodetest] < 0} {
return -code error "unknown node type \"$typetest\""
}
return [list $nodetest $typetest]
}
*,*,0,* {
# Node type test
if {[lsearch $nodeTypes $nodetest] < 0} {
return -code error "unknown node type \"$typetest\""
}
return [list $nodetest $literal]
}
default {
# Internal error?
return -code error "bad location step"
}
}
}
# xpath::join --
#
# Reconstitute an XPath location path from a
# Tcl list representation.
#
# Arguments:
# spath split path
#
# Results:
# Returns an Xpath location path
proc xpath::join spath {
return -code error "not yet implemented"
}
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