go-pkg-xmlx/src/document.go

// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

/*
 Author: Jim Teeuwen <jimteeuwen@gmail.com>

 This package wraps the standard XML library and uses it to build a node tree of
 any document you load. This allows you to look up nodes forwards and backwards,
 as well as perform search queries (no xpath support yet).

 Nodes now simply become collections and don't require you to read them in the
 order in which the xml.Parser finds them.

 xmlx.Document implements both these interfaces:
 
	type ILoader interface {
		LoadFile(string) os.Error;
		LoadString(string) os.Error;
		LoadStream(*io.Reader) os.Error;
	}

	type ISaver interface {
		SaveFile(string) os.Error;
		SaveString(string) (string, os.Error);
		SaveStream(*io.Writer) os.Error;
	}

 This allows you to load/save xml data to and from pretty much any source.

 The Document currently implements 2 simple search functions which allow you to
 look for specific nodes.
 
   Document.SelectNode(namespace, name string) *Node;
   Document.SelectNodes(namespace, name string) []*Node;
 
 SelectNode() returns the first, single node it finds matching the given name
 and namespace. SelectNodes() returns a slice containing all the matching nodes.
 
 Note that these search functions can be invoked on individual nodes as well.
 This allows you to search only a subset of the entire document.

*/
package xmlx

import "os"
import "io"
import "strings"
import "xml"
import "fmt"

type Document struct {
	Version		string;
	Encoding	string;
	StandAlone	string;
	SaveDocType	bool;
	Root		*Node;
}

func New() *Document {
	return &Document{
		Version: "1.0",
		Encoding: "utf-8",
		StandAlone: "yes",
		SaveDocType: true,
	}
}

func (this *Document) String() string {
	s, _ := this.SaveString();
	return s;
}


func (this *Document) SelectNode(namespace, name string) *Node {
	return this.Root.SelectNode(namespace, name);
}

func (this *Document) SelectNodes(namespace, name string) []*Node {
	return this.Root.SelectNodes(namespace, name);
}

// *****************************************************************************
// *** Satisfy ILoader interface
// *****************************************************************************
func (this *Document) LoadString(s string) (err os.Error) {
	xp := xml.NewParser(strings.NewReader(s));
	this.Root = NewNode(NT_ROOT);
	ct := this.Root;

	for {
		tok, err := xp.Token();
		if err != nil {
			return
		}

		t1, ok := tok.(xml.SyntaxError);
		if ok {
			err = os.NewError(t1.String());
			return;
		}

		t2, ok := tok.(xml.CharData);
		if ok {
			if ct != nil {
				ct.Value = strings.TrimSpace(string(t2))
			}
			continue
		}

		t3, ok := tok.(xml.Comment);
		if ok {
			t := NewNode(NT_COMMENT);
			t.Value = strings.TrimSpace(string(t3));
			if ct != nil {
				ct.AddChild(t)
			}
			continue
		}

		t4, ok := tok.(xml.Directive);
		if ok {
			t := NewNode(NT_DIRECTIVE);
			t.Value = strings.TrimSpace(string(t4));
			if ct != nil {
				ct.AddChild(t)
			}
			continue
		}

		t5, ok := tok.(xml.StartElement);
		if ok {
			t := NewNode(NT_ELEMENT);
			t.Name = t5.Name;
			t.Attributes = make([]Attr, len(t5.Attr));
			for i, v := range t5.Attr {
				t.Attributes[i].Name = v.Name;
				t.Attributes[i].Value = v.Value;
			}
			if ct != nil {
				ct.AddChild(t)
			}
			ct = t;
			continue
		}

		t6, ok := tok.(xml.ProcInst);
		if ok {
			if t6.Target == "xml" {	// xml doctype
				doctype := strings.TrimSpace(string(t6.Inst));
				
				/* // Not needed. There is only xml version 1.0
				pos := strings.Index(doctype, `version="`);
				if pos > -1 {
					this.Version = doctype[pos+len(`version="`) : len(doctype)];
					pos = strings.Index(this.Version, `"`);
					this.Version = this.Version[0:pos];
				}
				*/

				/* // Not needed. Any string we handle in Go is UTF8
				   // encoded. This means we will save UTF8 data as well. 
				pos = strings.Index(doctype, `encoding="`);
				if pos > -1 {
					this.Encoding = doctype[pos+len(`encoding="`) : len(doctype)];
					pos = strings.Index(this.Encoding, `"`);
					this.Encoding = this.Encoding[0:pos];
				}
				*/

				pos := strings.Index(doctype, `standalone="`);
				if pos > -1 {
					this.StandAlone = doctype[pos+len(`standalone="`) : len(doctype)];
					pos = strings.Index(this.StandAlone, `"`);
					this.StandAlone = this.StandAlone[0:pos];
				}
			} else {
				t := NewNode(NT_PROCINST);
				t.Target = strings.TrimSpace(t6.Target);
				t.Value = strings.TrimSpace(string(t6.Inst));
				if ct != nil {
					ct.AddChild(t)
				}
			}
			continue
		}

		_, ok = tok.(xml.EndElement);
		if ok {
			ct = ct.Parent;
			continue
		}
	}

	return;
}

func (this *Document) LoadFile(path string) (err os.Error) {
	file, err := os.Open(path, os.O_RDONLY, 0600);
	if err != nil {
		return
	}
	defer file.Close();

	content := "";
	buff := make([]byte, 256);
	for {
		_, err := file.Read(buff);
		if err != nil {
			break
		}
		content += string(buff);
	}

	err = this.LoadString(content);
	return;
}

func (this *Document) LoadStream(r *io.Reader) (err os.Error) {
	content := "";
	buff := make([]byte, 256);
	for {
		_, err := r.Read(buff);
		if err != nil {
			break
		}
		content += string(buff);
	}

	err = this.LoadString(content);
	return;
}

// *****************************************************************************
// *** Satisfy ISaver interface
// *****************************************************************************
func (this *Document) SaveFile(path string) (err os.Error) {
	file, err := os.Open(path, os.O_WRONLY | os.O_CREAT, 0600);
	if err != nil {
		return
	}
	defer file.Close();

	content, err  := this.SaveString();
	if err != nil {
		return
	}

	file.Write(strings.Bytes(content));
	return
}

func (this *Document) SaveString() (s string, err os.Error) {
	if this.SaveDocType {
		s = fmt.Sprintf(`<?xml version="%s" encoding="%s" standalone="%s"?>`,
			this.Version, this.Encoding, this.StandAlone)
	}

	s += this.Root.String();
	return;
}

func (this *Document) SaveStream(w *io.Writer) (err os.Error) {
	s, err := this.SaveString();
	if err != nil {
		return
	}
	w.Write(strings.Bytes(s));
	return;
}