Merge PR #88 from srebhan/string_join

Implement string-join function

README.md

@@ -49,7 +49,7 @@ Supported Features
 
 - `a/b` : For each node matching a, add the nodes matching b to the result.
 
-- `a//b` : For each node matching a, add the descendant nodes matching b to the result. 
+- `a//b` : For each node matching a, add the descendant nodes matching b to the result.
 
 - `//b` : Returns elements in the entire document matching b.
 
@@ -59,7 +59,7 @@ Supported Features
 
 - `(a/b)` : Selects all matches nodes as grouping set.
 
-#### Node Axes 
+#### Node Axes
 
 - `child::*` : The child axis selects children of the current node.
 
@@ -73,9 +73,9 @@ Supported Features
 
 - `preceding-sibling::*` : Selects nodes before the current node.
 
-- `following::*` : Selects the first matching node following in document order, excluding descendants. 
+- `following::*` : Selects the first matching node following in document order, excluding descendants.
 
-- `preceding::*` : Selects the first matching node preceding in document order, excluding ancestors. 
+- `preceding::*` : Selects the first matching node preceding in document order, excluding ancestors.
 
 - `parent::*` : Selects the parent if it matches. The '..' pattern from the core is equivalent to 'parent::node()'.
 
@@ -151,6 +151,7 @@ Supported Features
 `round()`| ✓ |
 `starts-with()`| ✓ |
 `string()`| ✓ |
+`string-join()`[^1]| ✓ |
 `string-length()`| ✓ |
 `substring()`| ✓ |
 `substring-after()`| ✓ |
@@ -159,4 +160,6 @@ Supported Features
 `system-property()`| ✗ |
 `translate()`| ✓ |
 `true()`| ✓ |
-`unparsed-entity-url()` | ✗ |
+`unparsed-entity-url()` | ✗ |
+
+[^1]: XPath-2.0 expression

build.go

@@ -450,6 +450,19 @@ func (b *builder) processFunctionNode(root *functionNode) (query, error) {
 			return nil, err
 		}
 		qyOutput = &transformFunctionQuery{Input: argQuery, Func: reverseFunc}
+	case "string-join":
+		if len(root.Args) != 2 {
+			return nil, fmt.Errorf("xpath: string-join(node-sets, separator) function requires node-set and argument")
+		}
+		argQuery, err := b.processNode(root.Args[0])
+		if err != nil {
+			return nil, err
+		}
+		arg1, err := b.processNode(root.Args[1])
+		if err != nil {
+			return nil, err
+		}
+		qyOutput = &functionQuery{Input: argQuery, Func: stringJoinFunc(arg1)}
 	default:
 		return nil, fmt.Errorf("not yet support this function %s()", root.FuncName)
 	}

func.go

@@ -614,3 +614,34 @@ func reverseFunc(q query, t iterator) func() NodeNavigator {
 		return node
 	}
 }
+
+// string-join is a XPath Node Set functions string-join(node-set, separator).
+func stringJoinFunc(arg1 query) func(query, iterator) interface{} {
+	return func(q query, t iterator) interface{} {
+		var separator string
+		switch v := functionArgs(arg1).Evaluate(t).(type) {
+		case string:
+			separator = v
+		case query:
+			node := v.Select(t)
+			if node != nil {
+				separator = node.Value()
+			}
+		}
+
+		q = functionArgs(q)
+		test := predicate(q)
+		var parts []string
+		switch v := q.Evaluate(t).(type) {
+		case string:
+			return v
+		case query:
+			for node := v.Select(t); node != nil; node = v.Select(t) {
+				if test(node) {
+					parts = append(parts, node.Value())
+				}
+			}
+		}
+		return strings.Join(parts, separator)
+	}
+}

xpath_test.go

@@ -352,6 +352,8 @@ func TestFunction(t *testing.T) {
 		`translate('The quick brown fox.', 'brown', 'red')`,
 		"The quick red fdx.",
 	)
+	testEval(t, html, `string-join(//li/a,';')`, "Home;about;login")
+	testEval(t, html, `string-join('some text',';')`, "some text")
 	// preceding-sibling::*
 	testXPath3(t, html, "//li[last()]/preceding-sibling::*[2]", selectNode(html, "//li[position()=2]"))
 	// preceding::
@@ -404,7 +406,9 @@ func TestPanic(t *testing.T) {
 	assertPanic(t, func() { testXPath3(t, html, "//title[substring(.,4,'')=0]", nil) })
 	assertPanic(t, func() { testXPath3(t, html, "//title[substring(.,4,4)=0]", nil) })
 	//assertPanic(t, func() { testXPath2(t, html, "//title[substring(child::*,0) = '']", 0) }) // Here substring return boolen (false), should it?
-
+	//string-join
+	assertPanic(t, func() { testXPath3(t, html, "string-join()", nil) })
+	assertPanic(t, func() { testXPath3(t, html, "string-join(//li/a)", nil) })
 }
 
 func TestEvaluate(t *testing.T) {