add has_attribute and the option required for attribute

Author: lindahua

README.md

@@ -203,7 +203,14 @@ has_attributes(e)    # whether e has attributes
 child_nodes(x)       # iterator of all child nodes of a node/element x
 child_elements(e)    # iterator of all child elements of e
 attributes(e)        # iterator of all attributes of e
-attribute(e, name)   # get the value of a named attribute
+
+has_attribute(e, name)  # whether a named attribute exists for e
+
+# get the value of a named attribute
+# when the attribute does not exist, it either 
+# throws an exception (when required is true)
+# or returns nothing (when required is false)
+attribute(e, name; required=false)                                         
 
 find_element(e, name)   # the first element of specified name under e
                         # return nothing is no such an element is found

src/LightXML.jl

@@ -8,8 +8,8 @@ module LightXML
 	# nodes
 	AbstractXMLNode, 
 	XMLAttr, XMLAttrIter, XMLNode, XMLNodeIter, XMLElement, XMLElementIter,
-	nodetype, value, content, attribute,
-	is_elementnode, is_textnode, is_commentnode, is_cdatanode,
+	nodetype, value, content, attribute, has_attribute,
+	is_elementnode, is_textnode, is_commentnode, is_cdatanode, is_blanknode,
 	child_nodes, has_children, attributes, has_attributes, child_elements,
 	find_element, get_elements_by_tagname,
 

src/clib.jl

@@ -39,10 +39,12 @@ _xcopystr(p::Xstr) = (r = bytestring(p); _xmlfree(p); r)
 # functions for nodes
 
 @lx2func xmlNodeGetContent
+@lx2func xmlHasProp
 @lx2func xmlGetProp
 @lx2func xmlFirstElementChild
 @lx2func xmlNextElementSibling
 @lx2func xmlNodeDump
+@lx2func xmlIsBlankNode
 
 @lx2func xmlNewNode
 @lx2func xmlAddChild

src/nodes.jl

@@ -142,6 +142,10 @@ name(nd::XMLNode) = bytestring(nd._struct.name)
 nodetype(nd::XMLNode) = nd._struct.nodetype
 has_children(nd::XMLNode) = (nd._struct.children != nullptr)
 
+# whether it is a white-space only text node
+is_blanknode(nd::XMLNode) = bool(ccall(xmlIsBlankNode, Cint, (Xptr,), nd.ptr))
+
+
 # iteration over children
 
 immutable XMLNodeIter
@@ -207,10 +211,22 @@ Base.show(io::IO, x::XMLElement) = Base.show(x.node)
 
 # attribute access
 
-function attribute(x::XMLElement, name::ASCIIString)
+function attribute(x::XMLElement, name::ASCIIString; required::Bool=false)
 	pv = ccall(xmlGetProp, Xstr, (Xptr, Xstr), x.node.ptr, name)
-	pv != nullptr || throw(XMLAttributeNotFound())
-	_xcopystr(pv)
+	if pv != nullptr
+		return _xcopystr(pv)
+	else
+		if required
+			throw(XMLAttributeNotFound())
+		else
+			return nothing
+		end
+	end
+end
+
+function has_attribute(x::XMLElement, name::ASCIIString)
+	p = ccall(xmlHasProp, Xptr, (Xptr, Xstr), x.node.ptr, name)
+	return p != nullptr
 end
 
 has_attributes(x::XMLElement) = (x.node._struct.attrs != nullptr)

test/parse.jl

@@ -52,9 +52,16 @@ rcs = collect(child_nodes(xroot))
 @test is_textnode(rcs[3])
 @test is_textnode(rcs[5])
 
+@test is_blanknode(rcs[1])
+@test is_blanknode(rcs[3])
+@test is_blanknode(rcs[5])
+
 @test is_elementnode(rcs[2])
 @test is_elementnode(rcs[4])
 
+@test !is_blanknode(rcs[2])
+@test !is_blanknode(rcs[4])
+
 xb1 = XMLElement(rcs[2])
 
 @test name(xb1) == "book"
@@ -83,8 +90,13 @@ xb2 = XMLElement(rcs[4])
 @test nodetype(xb2) == 1
 @test has_attributes(xb2)
 @test has_children(xb2)
+@test has_attribute(xb2, "category")
 @test attribute(xb2, "category") == "CHILDREN"
 
+@test !has_attribute(xb2, "wrongattr")
+@test is(attribute(xb2, "wrongattr"), nothing)
+@test_throws attribute(xb2, "wrongattr"; required=true)
+
 rces = get_elements_by_tagname(xroot, "book")
 @test length(rces) == 2
 @test isa(rces, Vector{XMLElement})