//*********************************************************************
// SPath grammar (JavaCC)
// Author: Shawn Bayern
// For JSTL reference implementation (Apache Jakarta Taglibs)


//*********************************************************************
// Configuration and boilerplate

options {
  STATIC = false;			// we'll need multiple instances
  JAVA_UNICODE_ESCAPE = true;		// XML uses Unicode too
}

PARSER_BEGIN(SPathParser)

package org.apache.taglibs.standard.extra.spath;

import java.util.Vector;

public class SPathParser {

  /** Simple command-line parser interface, primarily for testing. */
  public static void main(String args[]) throws ParseException
  {
    SPathParser parser = new SPathParser(System.in);
    Path p = parser.expression();
    java.util.List l = p.getSteps();

    // output for simple testing
    System.out.println();
    if (p instanceof AbsolutePath)
	System.out.println("Root: /");
    for (int i = 0; i < l.size(); i++) {
	Step s = (Step) l.get(i);
	System.out.print("Step: " + s.getName());
	if (s.isDepthUnlimited())
	    System.out.print("(*)");
	System.out.println();
    }
  }

  // custom constructor to accept a String
  public SPathParser(String x) {
    this(new StringReader(x));
  }

}

PARSER_END(SPathParser)

//*********************************************************************
// Literals

TOKEN :
{
  < LITERAL:
      ("\"" ((~["\"","\\"]) | ("\\" ( ["\\","\""] )))* "\"") |
      ("\'" ((~["\'","\\"]) | ("\\" ( ["\\","\'"] )))* "\'")
  >
}

//*********************************************************************
// Primitive identifiers

TOKEN :
{
  < QNAME:  (<NCNAME><COLON>)? (<NCNAME>) >
 |< NCNAME: (<LETTER> | <UNDERSCORE>) (<NCNAMECHAR>)* >
 |< NSWILDCARD: (<NCNAME><COLON><STAR>) >
 |< #NCNAMECHAR: (<LETTER>|<DIGIT>|<DOT>|<DASH>|<UNDERSCORE>|
		  <COMBINING_CHAR>|<EXTENDER>) >
 |< #LETTER:
      (
	["\u0041"-"\u005A"] | ["\u0061"-"\u007A"] | ["\u00C0"-"\u00D6"] |
	["\u00D8"-"\u00F6"] | ["\u00F8"-"\u00FF"] | ["\u0100"-"\u0131"] |
	["\u0134"-"\u013E"] | ["\u0141"-"\u0148"] | ["\u014A"-"\u017E"] |
	["\u0180"-"\u01C3"] | ["\u01CD"-"\u01F0"] | ["\u01F4"-"\u01F5"] |
	["\u01FA"-"\u0217"] | ["\u0250"-"\u02A8"] | ["\u02BB"-"\u02C1"] | 
	"\u0386" | ["\u0388"-"\u038A"] | "\u038C" | ["\u038E"-"\u03A1"] | 
	["\u03A3"-"\u03CE"] | ["\u03D0"-"\u03D6"] | "\u03DA" | "\u03DC" | 
	"\u03DE" | "\u03E0" | ["\u03E2"-"\u03F3"] | ["\u0401"-"\u040C"] | 
	["\u040E"-"\u044F"] | ["\u0451"-"\u045C"] | ["\u045E"-"\u0481"] | 
	["\u0490"-"\u04C4"] | ["\u04C7"-"\u04C8"] | ["\u04CB"-"\u04CC"] | 
	["\u04D0"-"\u04EB"] | ["\u04EE"-"\u04F5"] | ["\u04F8"-"\u04F9"] | 
	["\u0531"-"\u0556"] | "\u0559" | ["\u0561"-"\u0586"] | 
	["\u05D0"-"\u05EA"] | ["\u05F0"-"\u05F2"] | ["\u0621"-"\u063A"] | 
	["\u0641"-"\u064A"] | ["\u0671"-"\u06B7"] | ["\u06BA"-"\u06BE"] | 
	["\u06C0"-"\u06CE"] | ["\u06D0"-"\u06D3"] | "\u06D5" |
	["\u06E5"-"\u06E6"] | ["\u0905"-"\u0939"] | "\u093D" | 
	["\u0958"-"\u0961"] | ["\u0985"-"\u098C"] | ["\u098F"-"\u0990"] | 
	["\u0993"-"\u09A8"] | ["\u09AA"-"\u09B0"] | "\u09B2" | 
	["\u09B6"-"\u09B9"] | ["\u09DC"-"\u09DD"] | ["\u09DF"-"\u09E1"] | 
	["\u09F0"-"\u09F1"] | ["\u0A05"-"\u0A0A"] | ["\u0A0F"-"\u0A10"] | 
	["\u0A13"-"\u0A28"] | ["\u0A2A"-"\u0A30"] | ["\u0A32"-"\u0A33"] | 
	["\u0A35"-"\u0A36"] | ["\u0A38"-"\u0A39"] | ["\u0A59"-"\u0A5C"] | 
	"\u0A5E" | ["\u0A72"-"\u0A74"] | ["\u0A85"-"\u0A8B"] | "\u0A8D" | 
	["\u0A8F"-"\u0A91"] | ["\u0A93"-"\u0AA8"] | ["\u0AAA"-"\u0AB0"] | 
	["\u0AB2"-"\u0AB3"] | ["\u0AB5"-"\u0AB9"] | "\u0ABD" | "\u0AE0" | 
	["\u0B05"-"\u0B0C"] | ["\u0B0F"-"\u0B10"] | ["\u0B13"-"\u0B28"] | 
	["\u0B2A"-"\u0B30"] | ["\u0B32"-"\u0B33"] | ["\u0B36"-"\u0B39"] | 
	"\u0B3D" | ["\u0B5C"-"\u0B5D"] | ["\u0B5F"-"\u0B61"] | 
	["\u0B85"-"\u0B8A"] | ["\u0B8E"-"\u0B90"] | ["\u0B92"-"\u0B95"] | 
	["\u0B99"-"\u0B9A"] | "\u0B9C" | ["\u0B9E"-"\u0B9F"] | 
	["\u0BA3"-"\u0BA4"] | ["\u0BA8"-"\u0BAA"] | ["\u0BAE"-"\u0BB5"] | 
	["\u0BB7"-"\u0BB9"] | ["\u0C05"-"\u0C0C"] | ["\u0C0E"-"\u0C10"] | 
	["\u0C12"-"\u0C28"] | ["\u0C2A"-"\u0C33"] | ["\u0C35"-"\u0C39"] | 
	["\u0C60"-"\u0C61"] | ["\u0C85"-"\u0C8C"] | ["\u0C8E"-"\u0C90"] | 
	["\u0C92"-"\u0CA8"] | ["\u0CAA"-"\u0CB3"] | ["\u0CB5"-"\u0CB9"] | 
	"\u0CDE" | ["\u0CE0"-"\u0CE1"] | ["\u0D05"-"\u0D0C"] | 
	["\u0D0E"-"\u0D10"] | ["\u0D12"-"\u0D28"] | ["\u0D2A"-"\u0D39"] | 
	["\u0D60"-"\u0D61"] | ["\u0E01"-"\u0E2E"] | "\u0E30" | 
	["\u0E32"-"\u0E33"] | ["\u0E40"-"\u0E45"] | ["\u0E81"-"\u0E82"] | 
	"\u0E84" | ["\u0E87"-"\u0E88"] | "\u0E8A" | "\u0E8D" | 
	["\u0E94"-"\u0E97"] | ["\u0E99"-"\u0E9F"] | ["\u0EA2"-"\u0EA3"] | 
	"\u0EA5" | "\u0EA7" | ["\u0EAA"-"\u0EAB"] | ["\u0EAD"-"\u0EAE"] | 
	"\u0EB0" | ["\u0EB2"-"\u0EB3"] | "\u0EBD" | ["\u0EC0"-"\u0EC4"] | 
	["\u0F40"-"\u0F47"] | ["\u0F49"-"\u0F69"] | ["\u10A0"-"\u10C5"] | 
	["\u10D0"-"\u10F6"] | "\u1100" | ["\u1102"-"\u1103"] | 
	["\u1105"-"\u1107"] | "\u1109" | ["\u110B"-"\u110C"] | 
	["\u110E"-"\u1112"] | "\u113C" | "\u113E" | "\u1140" | "\u114C" | 
	"\u114E" | "\u1150" | ["\u1154"-"\u1155"] | "\u1159" | 
	["\u115F"-"\u1161"] | "\u1163" | "\u1165" | "\u1167" | "\u1169" | 
	["\u116D"-"\u116E"] | ["\u1172"-"\u1173"] | "\u1175" | 
	"\u119E" | "\u11A8" | "\u11AB" | ["\u11AE"-"\u11AF"] | 
	["\u11B7"-"\u11B8"] | "\u11BA" | ["\u11BC"-"\u11C2"] | "\u11EB" | 
	"\u11F0" | "\u11F9" | ["\u1E00"-"\u1E9B"] | ["\u1EA0"-"\u1EF9"] | 
	["\u1F00"-"\u1F15"] | ["\u1F18"-"\u1F1D"] | ["\u1F20"-"\u1F45"] | 
	["\u1F48"-"\u1F4D"] | ["\u1F50"-"\u1F57"] | "\u1F59" | "\u1F5B" | 
	"\u1F5D" | ["\u1F5F"-"\u1F7D"] | ["\u1F80"-"\u1FB4"] | 
	["\u1FB6"-"\u1FBC"] | "\u1FBE" | ["\u1FC2"-"\u1FC4"] |
	["\u1FC6"-"\u1FCC"] | ["\u1FD0"-"\u1FD3"] | ["\u1FD6"-"\u1FDB"] | 
	["\u1FE0"-"\u1FEC"] | ["\u1FF2"-"\u1FF4"] | ["\u1FF6"-"\u1FFC"] | 
	"\u2126" | ["\u212A"-"\u212B"] | "\u212E" | ["\u2180"-"\u2182"] | 
	["\u3041"-"\u3094"] | ["\u30A1"-"\u30FA"] | ["\u3105"-"\u312C"] | 
	["\uAC00"-"\uD7A3"] | ["\u4E00"-"\u9FA5"] | "\u3007" | 
	["\u3021"-"\u3029"] 
      )
  >
 |< #DIGIT:
      (
	["\u0030"-"\u0039"] | ["\u0660"-"\u0669"] | ["\u06F0"-"\u06F9"] |
	["\u0966"-"\u096F"] | ["\u09E6"-"\u09EF"] | ["\u0A66"-"\u0A6F"] |
	["\u0AE6"-"\u0AEF"] | ["\u0B66"-"\u0B6F"] | ["\u0BE7"-"\u0BEF"] |
	["\u0C66"-"\u0C6F"] | ["\u0CE6"-"\u0CEF"] | ["\u0D66"-"\u0D6F"] |
	["\u0E50"-"\u0E59"] | ["\u0ED0"-"\u0ED9"] | ["\u0F20"-"\u0F29"]
      )
  >
 |< #COMBINING_CHAR:
      (
	["\u0300"-"\u0345"] | ["\u0360"-"\u0361"] | ["\u0483"-"\u0486"] |
	["\u0591"-"\u05A1"] | ["\u05A3"-"\u05B9"] | ["\u05BB"-"\u05BD"] | 
	"\u05BF" | ["\u05C1"-"\u05C2"] | "\u05C4" | ["\u064B"-"\u0652"] | 
	"\u0670" | ["\u06D6"-"\u06DC"] | ["\u06DD"-"\u06DF"] | 
	["\u06E0"-"\u06E4"] | ["\u06E7"-"\u06E8"] | ["\u06EA"-"\u06ED"] | 
	["\u0901"-"\u0903"] | "\u093C" | ["\u093E"-"\u094C"] | "\u094D" | 
	["\u0951"-"\u0954"] | ["\u0962"-"\u0963"] | ["\u0981"-"\u0983"] | 
	"\u09BC" | "\u09BE" | "\u09BF" | ["\u09C0"-"\u09C4"] | 
	["\u09C7"-"\u09C8"] | ["\u09CB"-"\u09CD"] | "\u09D7" |
	["\u09E2"-"\u09E3"] | "\u0A02" | "\u0A3C" | "\u0A3E" | "\u0A3F" | 
	["\u0A40"-"\u0A42"] | ["\u0A47"-"\u0A48"] | ["\u0A4B"-"\u0A4D"] | 
	["\u0A70"-"\u0A71"] | ["\u0A81"-"\u0A83"] | "\u0ABC" | 
	["\u0ABE"-"\u0AC5"] | ["\u0AC7"-"\u0AC9"] | ["\u0ACB"-"\u0ACD"] | 
	["\u0B01"-"\u0B03"] | "\u0B3C" | ["\u0B3E"-"\u0B43"] | 
	["\u0B47"-"\u0B48"] | ["\u0B4B"-"\u0B4D"] | ["\u0B56"-"\u0B57"] | 
	["\u0B82"-"\u0B83"] | ["\u0BBE"-"\u0BC2"] | ["\u0BC6"-"\u0BC8"] | 
	["\u0BCA"-"\u0BCD"] | "\u0BD7" | ["\u0C01"-"\u0C03"] | 
	["\u0C3E"-"\u0C44"] | ["\u0C46"-"\u0C48"] | ["\u0C4A"-"\u0C4D"] | 
	["\u0C55"-"\u0C56"] | ["\u0C82"-"\u0C83"] | ["\u0CBE"-"\u0CC4"] | 
	["\u0CC6"-"\u0CC8"] | ["\u0CCA"-"\u0CCD"] | ["\u0CD5"-"\u0CD6"] | 
	["\u0D02"-"\u0D03"] | ["\u0D3E"-"\u0D43"] | ["\u0D46"-"\u0D48"] | 
	["\u0D4A"-"\u0D4D"] | "\u0D57" | "\u0E31" | ["\u0E34"-"\u0E3A"] | 
	["\u0E47"-"\u0E4E"] | "\u0EB1" | ["\u0EB4"-"\u0EB9"] | 
	["\u0EBB"-"\u0EBC"] | ["\u0EC8"-"\u0ECD"] | ["\u0F18"-"\u0F19"] | 
	"\u0F35" | "\u0F37" | "\u0F39" | "\u0F3E" | "\u0F3F" | 
	["\u0F71"-"\u0F84"] | ["\u0F86"-"\u0F8B"] | ["\u0F90"-"\u0F95"] | 
	"\u0F97" | ["\u0F99"-"\u0FAD"] | ["\u0FB1"-"\u0FB7"] | "\u0FB9" | 
	["\u20D0"-"\u20DC"] | "\u20E1" | ["\u302A"-"\u302F"] | "\u3099" | 
	"\u309A"
      ) >
 |< #EXTENDER:
      (
	"\u00B7" | "\u02D0" | "\u02D1" | "\u0387" | "\u0640" | "\u0E46" | 
	"\u0EC6" | "\u3005" | ["\u3031"-"\u3035"] | ["\u309D"-"\u309E"] | 
	["\u30FC"-"\u30FE"]
      ) >
 |< #UNDERSCORE: "_" >
 |< #DOT:        "." >
 |< #DASH:       "-" >
}

//*********************************************************************
// Separators

TOKEN :
{
  < SLASH: "/" >
 |< STAR:  "*" >
 |< COLON: ":" >
 |< START_BRACKET: "[" >
 |< END_BRACKET: "]" >
 |< AT: "@" >
 |< EQUALS: "=" >
}


//*********************************************************************
// Actual SPath grammar

Path expression():
{
  Path expr;
}
{
 ( LOOKAHEAD(absolutePath()) expr = absolutePath() <EOF> 
   | expr = relativePath() <EOF> )
 { return expr; }
}

AbsolutePath absolutePath():
{
  RelativePath relPath;
}
{
 ( <SLASH> relPath = relativePath() )
 { return new AbsolutePath(relPath); }
}

// as an example, we use recursion here to handle a list
RelativePath relativePath():
{
  RelativePath relPath = null;
  Step step;
}
{
 ( step = step() 
   (<SLASH> relPath = relativePath())? )
 {
   return new RelativePath(step, relPath);
 }
}

// as an example, we use inline code here to handle a list
/* 
 * (i'm doing something perhaps unusual here, including the <SLASH>
 * as if it were part of the step.  this mechanism for differentiating
 * '/' from '//' seems most natural, even if it is a bit unconventional.)
 */
Step step():
{
  Token slash = null;
  String nt;
  Vector pl = null;
  Predicate p;
}
{
 (  (slash = <SLASH>)?
    nt = nameTest()
    ( p = predicate()
	{
	  if (pl == null) pl = new Vector();
	  pl.add(p);
	 }
    )*
 )
 {
   // if 'slash != null', then we have '//' versus '/'
   return new Step(slash != null, nt, pl);
 }
}

String nameTest():
{
  Token name;
}
{
 ( name = <STAR> | name = <NSWILDCARD> | name = <QNAME> )
 { return name.toString(); }
}

Predicate predicate():
{
  Predicate p;
}
{
  ( <START_BRACKET> p = attributePredicate() <END_BRACKET> )
  { return p; }
}

Predicate attributePredicate():
{
  Token attname, target;
}
{
  ( <AT> attname = <QNAME> <EQUALS> target = <LITERAL> )
  { return new AttributePredicate(attname.toString(), target.toString()); }
}