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//------------------------------------------------------------------------------
// <copyright file="XPathScanner.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
// <owner current="true" primary="true">Microsoft</owner>
//------------------------------------------------------------------------------
namespace MS.Internal.Xml.XPath {
using System;
using System.Xml;
using System.Xml.XPath;
using System.Diagnostics;
using System.Globalization;
using System.Text;
using System.Collections;
internal sealed class XPathScanner {
private string xpathExpr;
private int xpathExprIndex;
private LexKind kind;
private char currentChar;
private string name;
private string prefix;
private string stringValue;
private double numberValue = double.NaN;
private bool canBeFunction;
private XmlCharType xmlCharType = XmlCharType.Instance;
public XPathScanner(string xpathExpr) {
if (xpathExpr == null) {
throw XPathException.Create(Res.Xp_ExprExpected, string.Empty);
}
this.xpathExpr = xpathExpr;
NextChar();
NextLex();
}
public string SourceText { get { return this.xpathExpr; } }
private char CurerntChar { get { return currentChar; } }
private bool NextChar() {
Debug.Assert(0 <= xpathExprIndex && xpathExprIndex <= xpathExpr.Length);
if (xpathExprIndex < xpathExpr.Length) {
currentChar = xpathExpr[xpathExprIndex ++];
return true;
}
else {
currentChar = '\0';
return false;
}
}
#if XML10_FIFTH_EDITION
private char PeekNextChar() {
Debug.Assert(0 <= xpathExprIndex && xpathExprIndex <= xpathExpr.Length);
if (xpathExprIndex < xpathExpr.Length) {
return xpathExpr[xpathExprIndex];
}
else {
Debug.Assert(xpathExprIndex == xpathExpr.Length);
return '\0';
}
}
#endif
public LexKind Kind { get { return this.kind; } }
public string Name {
get {
Debug.Assert(this.kind == LexKind.Name || this.kind == LexKind.Axe);
Debug.Assert(this.name != null);
return this.name;
}
}
public string Prefix {
get {
Debug.Assert(this.kind == LexKind.Name);
Debug.Assert(this.prefix != null);
return this.prefix;
}
}
public string StringValue {
get {
Debug.Assert(this.kind == LexKind.String);
Debug.Assert(this.stringValue != null);
return this.stringValue;
}
}
public double NumberValue {
get {
Debug.Assert(this.kind == LexKind.Number);
Debug.Assert(this.numberValue != double.NaN);
return this.numberValue;
}
}
// To parse PathExpr we need a way to distinct name from function.
// THis distinction can't be done without context: "or (1 != 0)" this this a function or 'or' in OrExp
public bool CanBeFunction {
get {
Debug.Assert(this.kind == LexKind.Name);
return this.canBeFunction;
}
}
void SkipSpace() {
while (xmlCharType.IsWhiteSpace(this.CurerntChar) && NextChar()) ;
}
public bool NextLex() {
SkipSpace();
switch (this.CurerntChar) {
case '\0' :
kind = LexKind.Eof;
return false;
case ',': case '@': case '(': case ')':
case '|': case '*': case '[': case ']':
case '+': case '-': case '=': case '#':
case '$':
kind = (LexKind) Convert.ToInt32(this.CurerntChar, CultureInfo.InvariantCulture);
NextChar();
break;
case '<':
kind = LexKind.Lt;
NextChar();
if (this.CurerntChar == '=') {
kind = LexKind.Le;
NextChar();
}
break;
case '>':
kind = LexKind.Gt;
NextChar();
if (this.CurerntChar == '=') {
kind = LexKind.Ge;
NextChar();
}
break;
case '!':
kind = LexKind.Bang;
NextChar();
if (this.CurerntChar == '=') {
kind = LexKind.Ne;
NextChar();
}
break;
case '.':
kind = LexKind.Dot;
NextChar();
if (this.CurerntChar == '.') {
kind = LexKind.DotDot;
NextChar();
}
else if (XmlCharType.IsDigit(this.CurerntChar)) {
kind = LexKind.Number;
numberValue = ScanFraction();
}
break;
case '/':
kind = LexKind.Slash;
NextChar();
if (this.CurerntChar == '/') {
kind = LexKind.SlashSlash;
NextChar();
}
break;
case '"':
case '\'':
this.kind = LexKind.String;
this.stringValue = ScanString();
break;
default:
if (XmlCharType.IsDigit(this.CurerntChar)) {
kind = LexKind.Number;
numberValue = ScanNumber();
}
else if (xmlCharType.IsStartNCNameSingleChar(this.CurerntChar)
#if XML10_FIFTH_EDITION
|| xmlCharType.IsNCNameHighSurrogateChar(this.CurerntChar)
#endif
) {
kind = LexKind.Name;
this.name = ScanName();
this.prefix = string.Empty;
// "foo:bar" is one lexem not three because it doesn't allow spaces in between
// We should distinct it from "foo::" and need process "foo ::" as well
if (this.CurerntChar == ':') {
NextChar();
// can be "foo:bar" or "foo::"
if (this.CurerntChar == ':') { // "foo::"
NextChar();
kind = LexKind.Axe;
}
else { // "foo:*", "foo:bar" or "foo: "
this.prefix = this.name;
if (this.CurerntChar == '*') {
NextChar();
this.name = "*";
}
else if (xmlCharType.IsStartNCNameSingleChar(this.CurerntChar)
#if XML10_FIFTH_EDITION
|| xmlCharType.IsNCNameHighSurrogateChar(this.CurerntChar)
#endif
) {
this.name = ScanName();
}
else {
throw XPathException.Create(Res.Xp_InvalidName, SourceText);
}
}
}
else {
SkipSpace();
if (this.CurerntChar == ':') {
NextChar();
// it can be "foo ::" or just "foo :"
if (this.CurerntChar == ':') {
NextChar();
kind = LexKind.Axe;
}
else {
throw XPathException.Create(Res.Xp_InvalidName, SourceText);
}
}
}
SkipSpace();
this.canBeFunction = (this.CurerntChar == '(');
}
else {
throw XPathException.Create(Res.Xp_InvalidToken, SourceText);
}
break;
}
return true;
}
private double ScanNumber() {
Debug.Assert(this.CurerntChar == '.' || XmlCharType.IsDigit(this.CurerntChar));
int start = xpathExprIndex - 1;
int len = 0;
while (XmlCharType.IsDigit(this.CurerntChar)) {
NextChar(); len ++;
}
if (this.CurerntChar == '.') {
NextChar(); len ++;
while (XmlCharType.IsDigit(this.CurerntChar)) {
NextChar(); len ++;
}
}
return XmlConvert.ToXPathDouble(this.xpathExpr.Substring(start, len));
}
private double ScanFraction() {
Debug.Assert(XmlCharType.IsDigit(this.CurerntChar));
int start = xpathExprIndex - 2;
Debug.Assert(0 <= start && this.xpathExpr[start] == '.');
int len = 1; // '.'
while (XmlCharType.IsDigit(this.CurerntChar)) {
NextChar(); len ++;
}
return XmlConvert.ToXPathDouble(this.xpathExpr.Substring(start, len));
}
private string ScanString() {
char endChar = this.CurerntChar;
NextChar();
int start = xpathExprIndex - 1;
int len = 0;
while(this.CurerntChar != endChar) {
if (! NextChar()) {
throw XPathException.Create(Res.Xp_UnclosedString);
}
len ++;
}
Debug.Assert(this.CurerntChar == endChar);
NextChar();
return this.xpathExpr.Substring(start, len);
}
private string ScanName() {
Debug.Assert(xmlCharType.IsStartNCNameSingleChar(this.CurerntChar)
#if XML10_FIFTH_EDITION
|| xmlCharType.IsNCNameHighSurrogateChar(this.CurerntChar)
#endif
);
int start = xpathExprIndex - 1;
int len = 0;
for (;;) {
if (xmlCharType.IsNCNameSingleChar(this.CurerntChar)) {
NextChar();
len ++;
}
#if XML10_FIFTH_EDITION
else if (xmlCharType.IsNCNameSurrogateChar(this.PeekNextChar(), this.CurerntChar)) {
NextChar();
NextChar();
len += 2;
}
#endif
else {
break;
}
}
return this.xpathExpr.Substring(start, len);
}
public enum LexKind {
Comma = ',',
Slash = '/',
At = '@',
Dot = '.',
LParens = '(',
RParens = ')',
LBracket = '[',
RBracket = ']',
Star = '*',
Plus = '+',
Minus = '-',
Eq = '=',
Lt = '<',
Gt = '>',
Bang = '!',
Dollar = '$',
Apos = '\'',
Quote = '"',
Union = '|',
Ne = 'N', // !=
Le = 'L', // <=
Ge = 'G', // >=
And = 'A', // &&
Or = 'O', // ||
DotDot = 'D', // ..
SlashSlash = 'S', // //
Name = 'n', // XML _Name
String = 's', // Quoted string constant
Number = 'd', // _Number constant
Axe = 'a', // Axe (like child::)
Eof = 'E',
};
}
}
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