Support for the XPath sub/- operator.

This commit is contained in:
Yorick Peterse 2014-08-29 09:41:17 +02:00
parent 89686b6cff
commit a70645fb89
2 changed files with 50 additions and 0 deletions

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@ -690,6 +690,22 @@ module Oga
return on_call_number(context, left) * on_call_number(context, right)
end
##
# Processes the `-` operator.
#
# This operator converts the left and right expressions to numbers and
# subtracts the right number of the left number.
#
# @param [Oga::XPath::Node] ast_node
# @param [Oga::XML::NodeSet] context
# @return [Float]
#
def on_sub(ast_node, context)
left, right = *ast_node
return on_call_number(context, left) - on_call_number(context, right)
end
##
# Delegates function calls to specific handlers.
#

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@ -0,0 +1,34 @@
require 'spec_helper'
describe Oga::XPath::Evaluator do
context 'subtraction operator' do
before do
@document = parse('<root><a>2</a><b>3</b></root>')
@evaluator = described_class.new(@document)
end
example 'subtract two numbers' do
@evaluator.evaluate('2 - 3').should == -1.0
end
example 'subtract a number and a string' do
@evaluator.evaluate('2 - "3"').should == -1.0
end
example 'subtract two strings' do
@evaluator.evaluate('"2" - "3"').should == -1.0
end
example 'subtract a node set and a number' do
@evaluator.evaluate('root/a - 3').should == -1.0
end
example 'subtract two node sets' do
@evaluator.evaluate('root/a - root/b').should == -1.0
end
example 'return NaN when trying to subtract invalid values' do
@evaluator.evaluate('"" - 1').should be_nan
end
end
end