Added ability to manipulate HTML-attributes with AST

attributes.go

@@ -0,0 +1,92 @@
+package blackfriday
+
+import "strings"
+
+// attr - Abstraction for html attribute
+type attr []string
+
+// Add - adds one more attribute value
+func (a attr) add(value string) attr {
+	for _, item := range a {
+		if item == value {
+			return a
+		}
+	}
+	return append(a, value)
+}
+
+// Remove - removes given value from attribute
+func (a attr) remove(value string) attr {
+	for i := range a {
+		if a[i] == value {
+			return append(a[:i], a[i+1:]...)
+		}
+	}
+	return a
+}
+
+func (a attr) String() string {
+	return strings.Join(a, " ")
+}
+
+// Attributes - store for many attributes
+type Attributes struct {
+	attrsMap map[string]attr
+	keys     []string
+}
+
+// NewAttributes - creates new Attributes instance
+func NewAttributes() *Attributes {
+	return &Attributes{
+		attrsMap: make(map[string]attr),
+	}
+}
+
+// Add - adds attribute if not exists and sets value for it
+func (a *Attributes) Add(name, value string) *Attributes {
+	if _, ok := a.attrsMap[name]; !ok {
+		a.attrsMap[name] = make(attr, 0)
+		a.keys = append(a.keys, name)
+	}
+
+	a.attrsMap[name] = a.attrsMap[name].add(value)
+	return a
+}
+
+// Remove - removes attribute by name
+func (a *Attributes) Remove(name string) *Attributes {
+	for i := range a.keys {
+		if a.keys[i] == name {
+			a.keys = append(a.keys[:i], a.keys[i+1:]...)
+		}
+	}
+
+	delete(a.attrsMap, name)
+	return a
+}
+
+// RemoveValue - removes given value from attribute by name
+// If given attribues become empty it alose removes entire attribute
+func (a *Attributes) RemoveValue(name, value string) *Attributes {
+	if attr, ok := a.attrsMap[name]; ok {
+		a.attrsMap[name] = attr.remove(value)
+		if len(a.attrsMap[name]) == 0 {
+			a.Remove(name)
+		}
+	}
+	return a
+}
+
+// Empty - checks if attributes is empty
+func (a *Attributes) Empty() bool {
+	return len(a.keys) == 0
+}
+
+func (a *Attributes) String() string {
+	r := []string{}
+	for _, attrName := range a.keys {
+		r = append(r, attrName+"=\""+a.attrsMap[attrName].String()+"\"")
+	}
+
+	return strings.Join(r, " ")
+}

attributes_test.go

@@ -0,0 +1,132 @@
+package blackfriday
+
+import (
+	"bytes"
+	"testing"
+)
+
+func TestEmtyAttributes(t *testing.T) {
+	a := NewAttributes()
+	r := a.String()
+	e := ""
+	if r != e {
+		t.Errorf("Expected: %s\nActual: %s\n", e, r)
+	}
+}
+
+func TestAddOneAttribute(t *testing.T) {
+	a := NewAttributes()
+	a.Add("class", "wrapper")
+	r := a.String()
+	e := "class=\"wrapper\""
+	if r != e {
+		t.Errorf("Expected: %s\nActual: %s\n", e, r)
+	}
+}
+
+func TestAddFewValuesToOneAttribute(t *testing.T) {
+	a := NewAttributes()
+	a.Add("class", "wrapper").Add("class", "-with-image")
+	r := a.String()
+	e := "class=\"wrapper -with-image\""
+	if r != e {
+		t.Errorf("Expected: %s\nActual: %s\n", e, r)
+	}
+}
+
+func TestAddSameValueToAttribute(t *testing.T) {
+	a := NewAttributes()
+	a.Add("class", "wrapper").Add("class", "wrapper")
+	r := a.String()
+	e := "class=\"wrapper\""
+	if r != e {
+		t.Errorf("Expected: %s\nActual: %s\n", e, r)
+	}
+}
+
+func TestRemoveValueFromOneAttribute(t *testing.T) {
+	a := NewAttributes()
+	a.Add("class", "wrapper").Add("class", "-with-image")
+	a.RemoveValue("class", "wrapper")
+	r := a.String()
+	e := "class=\"-with-image\""
+	if r != e {
+		t.Errorf("Expected: %s\nActual: %s\n", e, r)
+	}
+}
+
+func TestRemoveWholeAttribute(t *testing.T) {
+	a := NewAttributes()
+	a.Add("class", "wrapper")
+	a.Remove("class")
+	r := a.String()
+	e := ""
+	if r != e {
+		t.Errorf("Expected: %s\nActual: %s\n", e, r)
+	}
+}
+
+func TestRemoveWholeAttributeByValue(t *testing.T) {
+	a := NewAttributes()
+	a.Add("class", "wrapper")
+	a.RemoveValue("class", "wrapper")
+	r := a.String()
+	e := ""
+	if r != e {
+		t.Errorf("Expected: %s\nActual: %s\n", e, r)
+	}
+}
+
+func TestAddFewAttributes(t *testing.T) {
+	a := NewAttributes()
+	a.Add("class", "wrapper").Add("id", "main-block")
+	r := a.String()
+	e := "class=\"wrapper\" id=\"main-block\""
+	if r != e {
+		t.Errorf("Expected: %s\nActual: %s\n", e, r)
+	}
+}
+
+func TestAddComplexAttributes(t *testing.T) {
+	a := NewAttributes()
+	a.
+		Add("style", "background: #fff;").
+		Add("style", "font-size: 14px;").
+		Add("data-test-id", "block")
+	r := a.String()
+	e := "style=\"background: #fff; font-size: 14px;\" data-test-id=\"block\""
+	if r != e {
+		t.Errorf("Expected: %s\nActual: %s\n", e, r)
+	}
+}
+
+func TestASTModification(t *testing.T) {
+	input := "\nPicture signature\n![alt text](/p.jpg)\n"
+	expected := "<p class=\"img\">Picture signature\n<img src=\"/p.jpg\" alt=\"alt text\" /></p>\n"
+
+	r := NewHTMLRenderer(HTMLRendererParameters{
+		Flags: CommonHTMLFlags,
+	})
+	var buf bytes.Buffer
+	optList := []Option{
+		WithRenderer(r),
+		WithExtensions(CommonExtensions)}
+	parser := New(optList...)
+	ast := parser.Parse([]byte(input))
+	r.RenderHeader(&buf, ast)
+	ast.Walk(func(node *Node, entering bool) WalkStatus {
+		if node.Type == Image && entering && node.Parent.Type == Paragraph {
+			node.Parent.Attributes.Add("class", "img")
+		}
+		return GoToNext
+	})
+	ast.Walk(func(node *Node, entering bool) WalkStatus {
+		return r.RenderNode(&buf, node, entering)
+	})
+	r.RenderFooter(&buf, ast)
+	actual := buf.String()
+
+	if actual != expected {
+		t.Errorf("Expected: %s\nActual: %s\n", expected, actual)
+	}
+}