Mini Shell
# frozen_string_literal: false
require 'rexml/namespace'
require 'rexml/xmltokens'
require 'rexml/attribute'
require 'rexml/syncenumerator'
require 'rexml/parsers/xpathparser'
class Object
# provides a unified +clone+ operation, for REXML::XPathParser
# to use across multiple Object types
def dclone
clone
end
end
class Symbol
# provides a unified +clone+ operation, for REXML::XPathParser
# to use across multiple Object types
def dclone ; self ; end
end
class Integer
# provides a unified +clone+ operation, for REXML::XPathParser
# to use across multiple Object types
def dclone ; self ; end
end
class Float
# provides a unified +clone+ operation, for REXML::XPathParser
# to use across multiple Object types
def dclone ; self ; end
end
class Array
# provides a unified +clone+ operation, for REXML::XPathParser
# to use across multiple Object+ types
def dclone
klone = self.clone
klone.clear
self.each{|v| klone << v.dclone}
klone
end
end
module REXML
# You don't want to use this class. Really. Use XPath, which is a wrapper
# for this class. Believe me. You don't want to poke around in here.
# There is strange, dark magic at work in this code. Beware. Go back! Go
# back while you still can!
class XPathParser
include XMLTokens
LITERAL = /^'([^']*)'|^"([^"]*)"/u
def initialize( )
@parser = REXML::Parsers::XPathParser.new
@namespaces = nil
@variables = {}
end
def namespaces=( namespaces={} )
Functions::namespace_context = namespaces
@namespaces = namespaces
end
def variables=( vars={} )
Functions::variables = vars
@variables = vars
end
def parse path, nodeset
path_stack = @parser.parse( path )
match( path_stack, nodeset )
end
def get_first path, nodeset
path_stack = @parser.parse( path )
first( path_stack, nodeset )
end
def predicate path, nodeset
path_stack = @parser.parse( path )
expr( path_stack, nodeset )
end
def []=( variable_name, value )
@variables[ variable_name ] = value
end
# Performs a depth-first (document order) XPath search, and returns the
# first match. This is the fastest, lightest way to return a single result.
#
# FIXME: This method is incomplete!
def first( path_stack, node )
return nil if path.size == 0
case path[0]
when :document
# do nothing
return first( path[1..-1], node )
when :child
for c in node.children
r = first( path[1..-1], c )
return r if r
end
when :qname
name = path[2]
if node.name == name
return node if path.size == 3
return first( path[3..-1], node )
else
return nil
end
when :descendant_or_self
r = first( path[1..-1], node )
return r if r
for c in node.children
r = first( path, c )
return r if r
end
when :node
return first( path[1..-1], node )
when :any
return first( path[1..-1], node )
end
return nil
end
def match( path_stack, nodeset )
r = expr( path_stack, nodeset )
r
end
private
# Returns a String namespace for a node, given a prefix
# The rules are:
#
# 1. Use the supplied namespace mapping first.
# 2. If no mapping was supplied, use the context node to look up the namespace
def get_namespace( node, prefix )
if @namespaces
return @namespaces[prefix] || ''
else
return node.namespace( prefix ) if node.node_type == :element
return ''
end
end
# Expr takes a stack of path elements and a set of nodes (either a Parent
# or an Array and returns an Array of matching nodes
ALL = [ :attribute, :element, :text, :processing_instruction, :comment ]
ELEMENTS = [ :element ]
def expr( path_stack, nodeset, context=nil )
node_types = ELEMENTS
return nodeset if path_stack.length == 0 || nodeset.length == 0
while path_stack.length > 0
if nodeset.length == 0
path_stack.clear
return []
end
case (op = path_stack.shift)
when :document
nodeset = [ nodeset[0].root_node ]
when :qname
prefix = path_stack.shift
name = path_stack.shift
nodeset.delete_if do |node|
# FIXME: This DOUBLES the time XPath searches take
ns = get_namespace( node, prefix )
if node.node_type == :element
if node.name == name
end
end
!(node.node_type == :element and
node.name == name and
node.namespace == ns )
end
node_types = ELEMENTS
when :any
nodeset.delete_if { |node| !node_types.include?(node.node_type) }
when :self
# This space left intentionally blank
when :processing_instruction
target = path_stack.shift
nodeset.delete_if do |node|
(node.node_type != :processing_instruction) or
( target!='' and ( node.target != target ) )
end
when :text
nodeset.delete_if { |node| node.node_type != :text }
when :comment
nodeset.delete_if { |node| node.node_type != :comment }
when :node
# This space left intentionally blank
node_types = ALL
when :child
new_nodeset = []
nt = nil
nodeset.each do |node|
nt = node.node_type
new_nodeset += node.children if nt == :element or nt == :document
end
nodeset = new_nodeset
node_types = ELEMENTS
when :literal
return path_stack.shift
when :attribute
new_nodeset = []
case path_stack.shift
when :qname
prefix = path_stack.shift
name = path_stack.shift
for element in nodeset
if element.node_type == :element
attrib = element.attribute( name, get_namespace(element, prefix) )
new_nodeset << attrib if attrib
end
end
when :any
for element in nodeset
if element.node_type == :element
new_nodeset += element.attributes.to_a
end
end
end
nodeset = new_nodeset
when :parent
nodeset = nodeset.collect{|n| n.parent}.compact
#nodeset = expr(path_stack.dclone, nodeset.collect{|n| n.parent}.compact)
node_types = ELEMENTS
when :ancestor
new_nodeset = []
nodeset.each do |node|
while node.parent
node = node.parent
new_nodeset << node unless new_nodeset.include? node
end
end
nodeset = new_nodeset
node_types = ELEMENTS
when :ancestor_or_self
new_nodeset = []
nodeset.each do |node|
if node.node_type == :element
new_nodeset << node
while ( node.parent )
node = node.parent
new_nodeset << node unless new_nodeset.include? node
end
end
end
nodeset = new_nodeset
node_types = ELEMENTS
when :predicate
new_nodeset = []
subcontext = { :size => nodeset.size }
pred = path_stack.shift
nodeset.each_with_index { |node, index|
subcontext[ :node ] = node
subcontext[ :index ] = index+1
pc = pred.dclone
result = expr( pc, [node], subcontext )
result = result[0] if result.kind_of? Array and result.length == 1
if result.kind_of? Numeric
new_nodeset << node if result == (index+1)
elsif result.instance_of? Array
if result.size > 0 and result.inject(false) {|k,s| s or k}
new_nodeset << node if result.size > 0
end
else
new_nodeset << node if result
end
}
nodeset = new_nodeset
=begin
predicate = path_stack.shift
ns = nodeset.clone
result = expr( predicate, ns )
if result.kind_of? Array
nodeset = result.zip(ns).collect{|m,n| n if m}.compact
else
nodeset = result ? nodeset : []
end
=end
when :descendant_or_self
rv = descendant_or_self( path_stack, nodeset )
path_stack.clear
nodeset = rv
node_types = ELEMENTS
when :descendant
results = []
nt = nil
nodeset.each do |node|
nt = node.node_type
results += expr( path_stack.dclone.unshift( :descendant_or_self ),
node.children ) if nt == :element or nt == :document
end
nodeset = results
node_types = ELEMENTS
when :following_sibling
results = []
nodeset.each do |node|
next if node.parent.nil?
all_siblings = node.parent.children
current_index = all_siblings.index( node )
following_siblings = all_siblings[ current_index+1 .. -1 ]
results += expr( path_stack.dclone, following_siblings )
end
nodeset = results
when :preceding_sibling
results = []
nodeset.each do |node|
next if node.parent.nil?
all_siblings = node.parent.children
current_index = all_siblings.index( node )
preceding_siblings = all_siblings[ 0, current_index ].reverse
results += preceding_siblings
end
nodeset = results
node_types = ELEMENTS
when :preceding
new_nodeset = []
nodeset.each do |node|
new_nodeset += preceding( node )
end
nodeset = new_nodeset
node_types = ELEMENTS
when :following
new_nodeset = []
nodeset.each do |node|
new_nodeset += following( node )
end
nodeset = new_nodeset
node_types = ELEMENTS
when :namespace
new_nodeset = []
prefix = path_stack.shift
nodeset.each do |node|
if (node.node_type == :element or node.node_type == :attribute)
if @namespaces
namespaces = @namespaces
elsif (node.node_type == :element)
namespaces = node.namespaces
else
namespaces = node.element.namesapces
end
if (node.namespace == namespaces[prefix])
new_nodeset << node
end
end
end
nodeset = new_nodeset
when :variable
var_name = path_stack.shift
return @variables[ var_name ]
# :and, :or, :eq, :neq, :lt, :lteq, :gt, :gteq
# TODO: Special case for :or and :and -- not evaluate the right
# operand if the left alone determines result (i.e. is true for
# :or and false for :and).
when :eq, :neq, :lt, :lteq, :gt, :gteq, :or
left = expr( path_stack.shift, nodeset.dup, context )
right = expr( path_stack.shift, nodeset.dup, context )
res = equality_relational_compare( left, op, right )
return res
when :and
left = expr( path_stack.shift, nodeset.dup, context )
return [] unless left
if left.respond_to?(:inject) and !left.inject(false) {|a,b| a | b}
return []
end
right = expr( path_stack.shift, nodeset.dup, context )
res = equality_relational_compare( left, op, right )
return res
when :div
left = Functions::number(expr(path_stack.shift, nodeset, context)).to_f
right = Functions::number(expr(path_stack.shift, nodeset, context)).to_f
return (left / right)
when :mod
left = Functions::number(expr(path_stack.shift, nodeset, context )).to_f
right = Functions::number(expr(path_stack.shift, nodeset, context )).to_f
return (left % right)
when :mult
left = Functions::number(expr(path_stack.shift, nodeset, context )).to_f
right = Functions::number(expr(path_stack.shift, nodeset, context )).to_f
return (left * right)
when :plus
left = Functions::number(expr(path_stack.shift, nodeset, context )).to_f
right = Functions::number(expr(path_stack.shift, nodeset, context )).to_f
return (left + right)
when :minus
left = Functions::number(expr(path_stack.shift, nodeset, context )).to_f
right = Functions::number(expr(path_stack.shift, nodeset, context )).to_f
return (left - right)
when :union
left = expr( path_stack.shift, nodeset, context )
right = expr( path_stack.shift, nodeset, context )
return (left | right)
when :neg
res = expr( path_stack, nodeset, context )
return -(res.to_f)
when :not
when :function
func_name = path_stack.shift.tr('-','_')
arguments = path_stack.shift
subcontext = context ? nil : { :size => nodeset.size }
res = []
cont = context
nodeset.each_with_index { |n, i|
if subcontext
subcontext[:node] = n
subcontext[:index] = i
cont = subcontext
end
arg_clone = arguments.dclone
args = arg_clone.collect { |arg|
expr( arg, [n], cont )
}
Functions.context = cont
res << Functions.send( func_name, *args )
}
return res
end
end # while
return nodeset
end
##########################################################
# FIXME
# The next two methods are BAD MOJO!
# This is my achilles heel. If anybody thinks of a better
# way of doing this, be my guest. This really sucks, but
# it is a wonder it works at all.
# ########################################################
def descendant_or_self( path_stack, nodeset )
rs = []
d_o_s( path_stack, nodeset, rs )
document_order(rs.flatten.compact)
#rs.flatten.compact
end
def d_o_s( p, ns, r )
nt = nil
ns.each_index do |i|
n = ns[i]
x = expr( p.dclone, [ n ] )
nt = n.node_type
d_o_s( p, n.children, x ) if nt == :element or nt == :document and n.children.size > 0
r.concat(x) if x.size > 0
end
end
# Reorders an array of nodes so that they are in document order
# It tries to do this efficiently.
#
# FIXME: I need to get rid of this, but the issue is that most of the XPath
# interpreter functions as a filter, which means that we lose context going
# in and out of function calls. If I knew what the index of the nodes was,
# I wouldn't have to do this. Maybe add a document IDX for each node?
# Problems with mutable documents. Or, rewrite everything.
def document_order( array_of_nodes )
new_arry = []
array_of_nodes.each { |node|
node_idx = []
np = node.node_type == :attribute ? node.element : node
while np.parent and np.parent.node_type == :element
node_idx << np.parent.index( np )
np = np.parent
end
new_arry << [ node_idx.reverse, node ]
}
new_arry.sort{ |s1, s2| s1[0] <=> s2[0] }.collect{ |s| s[1] }
end
def recurse( nodeset, &block )
for node in nodeset
yield node
recurse( node, &block ) if node.node_type == :element
end
end
# Builds a nodeset of all of the preceding nodes of the supplied node,
# in reverse document order
# preceding:: includes every element in the document that precedes this node,
# except for ancestors
def preceding( node )
ancestors = []
p = node.parent
while p
ancestors << p
p = p.parent
end
acc = []
p = preceding_node_of( node )
while p
if ancestors.include? p
ancestors.delete(p)
else
acc << p
end
p = preceding_node_of( p )
end
acc
end
def preceding_node_of( node )
psn = node.previous_sibling_node
if psn.nil?
if node.parent.nil? or node.parent.class == Document
return nil
end
return node.parent
#psn = preceding_node_of( node.parent )
end
while psn and psn.kind_of? Element and psn.children.size > 0
psn = psn.children[-1]
end
psn
end
def following( node )
acc = []
p = next_sibling_node( node )
while p
acc << p
p = following_node_of( p )
end
acc
end
def following_node_of( node )
if node.kind_of? Element and node.children.size > 0
return node.children[0]
end
return next_sibling_node(node)
end
def next_sibling_node(node)
psn = node.next_sibling_node
while psn.nil?
if node.parent.nil? or node.parent.class == Document
return nil
end
node = node.parent
psn = node.next_sibling_node
end
return psn
end
def norm b
case b
when true, false
return b
when 'true', 'false'
return Functions::boolean( b )
when /^\d+(\.\d+)?$/
return Functions::number( b )
else
return Functions::string( b )
end
end
def equality_relational_compare( set1, op, set2 )
if set1.kind_of? Array and set2.kind_of? Array
if set1.size == 1 and set2.size == 1
set1 = set1[0]
set2 = set2[0]
elsif set1.size == 0 or set2.size == 0
nd = set1.size==0 ? set2 : set1
rv = nd.collect { |il| compare( il, op, nil ) }
return rv
else
res = []
SyncEnumerator.new( set1, set2 ).each { |i1, i2|
i1 = norm( i1 )
i2 = norm( i2 )
res << compare( i1, op, i2 )
}
return res
end
end
# If one is nodeset and other is number, compare number to each item
# in nodeset s.t. number op number(string(item))
# If one is nodeset and other is string, compare string to each item
# in nodeset s.t. string op string(item)
# If one is nodeset and other is boolean, compare boolean to each item
# in nodeset s.t. boolean op boolean(item)
if set1.kind_of? Array or set2.kind_of? Array
if set1.kind_of? Array
a = set1
b = set2
else
a = set2
b = set1
end
case b
when true, false
return a.collect {|v| compare( Functions::boolean(v), op, b ) }
when Numeric
return a.collect {|v| compare( Functions::number(v), op, b )}
when /^\d+(\.\d+)?$/
b = Functions::number( b )
return a.collect {|v| compare( Functions::number(v), op, b )}
else
b = Functions::string( b )
return a.collect { |v| compare( Functions::string(v), op, b ) }
end
else
# If neither is nodeset,
# If op is = or !=
# If either boolean, convert to boolean
# If either number, convert to number
# Else, convert to string
# Else
# Convert both to numbers and compare
s1 = set1.to_s
s2 = set2.to_s
if s1 == 'true' or s1 == 'false' or s2 == 'true' or s2 == 'false'
set1 = Functions::boolean( set1 )
set2 = Functions::boolean( set2 )
else
if op == :eq or op == :neq
if s1 =~ /^\d+(\.\d+)?$/ or s2 =~ /^\d+(\.\d+)?$/
set1 = Functions::number( s1 )
set2 = Functions::number( s2 )
else
set1 = Functions::string( set1 )
set2 = Functions::string( set2 )
end
else
set1 = Functions::number( set1 )
set2 = Functions::number( set2 )
end
end
return compare( set1, op, set2 )
end
return false
end
def compare a, op, b
case op
when :eq
a == b
when :neq
a != b
when :lt
a < b
when :lteq
a <= b
when :gt
a > b
when :gteq
a >= b
when :and
a and b
when :or
a or b
else
false
end
end
end
end
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