/*
 * TinyJS
 *
 * A single-file Javascript-alike engine
 *
 * Authored By Gordon Williams <gw@pur3.co.uk>
 *
 * Copyright (C) 2009 Pur3 Ltd
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

/* Version 0.1  :  (gw) First published on Google Code
   Version 0.11 :  Making sure the 'root' variable never changes
                   'symbol_base' added for the current base of the sybmbol table
   Version 0.12 :  Added findChildOrCreate, changed string passing to use references
                   Fixed broken string encoding in getJSString()
                   Removed getInitCode and added getJSON instead
                   Added nil
                   Added rough JSON parsing
                   Improved example app
   Version 0.13 :  Added tokenEnd/tokenLastEnd to lexer to avoid parsing whitespace
                   Ability to define functions without names
                   Can now do "var mine = function(a,b) { ... };"
                   Slightly better 'trace' function
                   Added findChildOrCreateByPath function
                   Added simple test suite
                   Added skipping of blocks when not executing
   Version 0.14 :  Added parsing of more number types
                   Added parsing of string defined with '
                   Changed nil to null as per spec, added 'undefined'
                   Now set variables with the correct scope, and treat unknown
                              as 'undefined' rather than failing
                   Added proper (I hope) handling of null and undefined
                   Added === check
   Version 0.15 :  Fix for possible memory leaks
   Version 0.16 :  Removal of un-needed findRecursive calls
                   symbol_base removed and replaced with 'scopes' stack
                   Added reference counting a proper tree structure
                       (Allowing pass by reference)
                   Allowed JSON output to output IDs, not strings
                   Added get/set for array indices
                   Changed Callbacks to include user data pointer
                   Added some support for objects
                   Added more Java-esque builtin functions
   Version 0.17 :  Now we don't deepCopy the parent object of the class
                   Added JSON.stringify and eval()
                   Nicer JSON indenting
                   Fixed function output in JSON
                   Added evaluateComplex
                   Fixed some reentrancy issues with evaluate/execute
   Version 0.18 :  Fixed some issues with code being executed when it shouldn't
   Version 0.19 :  Added array.length
                   Changed '__parent' to 'prototype' to bring it more in line with javascript
   Version 0.20 :  Added '%' operator
   Version 0.21 :  Added array type
                   String.length() no more - now String.length
                   Added extra constructors to reduce confusion
                   Fixed checks against undefined

    NOTE: This doesn't support constructors for objects
          Recursive loops of data such as a.foo = a; fail to be garbage collected
          'length' cannot be set
          There is no ternary operator implemented yet
	  The postfix increment operator returns the current value, not the previous as it should.
 */

#include "TinyJS.h"
#include <assert.h>

#define ASSERT(X) assert(X)
/* Frees the given link IF it isn't owned by anything else */
#define CLEAN(x) { CScriptVarLink *__v = x; if (__v && !__v->owned) { delete __v; } }
/* Create a LINK to point to VAR and free the old link.
 * BUT this is more clever - it tries to keep the old link if it's not owned to save allocations */
#define CREATE_LINK(LINK, VAR) { if (!LINK || LINK->owned) LINK = new CScriptVarLink(VAR); else LINK->replaceWith(VAR); }

#include <string>
#include <string.h>
#include <sstream>
#include <cstdlib>
#include <stdio.h>

using namespace std;

#ifdef __GNUC__
#define vsprintf_s vsnprintf
#define sprintf_s snprintf
#endif

// ----------------------------------------------------------------------------------- Memory Debug

//#define DEBUG_MEMORY 1

#if DEBUG_MEMORY

vector<CScriptVar*> allocatedVars;
vector<CScriptVarLink*> allocatedLinks;

void mark_allocated(CScriptVar *v) {
    allocatedVars.push_back(v);
}

void mark_deallocated(CScriptVar *v) {
    for (size_t i=0;i<allocatedVars.size();i++) {
      if (allocatedVars[i] == v) {
        allocatedVars.erase(allocatedVars.begin()+i);
        break;
      }
    }
}

void mark_allocated(CScriptVarLink *v) {
    allocatedLinks.push_back(v);
}

void mark_deallocated(CScriptVarLink *v) {
    for (size_t i=0;i<allocatedLinks.size();i++) {
      if (allocatedLinks[i] == v) {
        allocatedLinks.erase(allocatedLinks.begin()+i);
        break;
      }
    }
}

void show_allocated() {
    for (size_t i=0;i<allocatedVars.size();i++) {
      printf("ALLOCATED, %d refs\n", allocatedVars[i]->getRefs());
      allocatedVars[i]->trace("  ");
    }
    for (size_t i=0;i<allocatedLinks.size();i++) {
      printf("ALLOCATED LINK %s, allocated[%d] to \n", allocatedLinks[i]->name.c_str(), allocatedLinks[i]->var->getRefs());
      allocatedLinks[i]->var->trace("  ");
    }
    allocatedVars.clear();
    allocatedLinks.clear();
}

#endif

// ----------------------------------------------------------------------------------- Utils
bool isWhitespace(char ch) {
    return (ch==' ') || (ch=='\t') || (ch=='\n') || (ch=='\r');
}

bool isNumeric(char ch) {
    return (ch>='0') && (ch<='9');
}
bool isNumber(const string &str) {
    for (size_t i=0;i<str.size();i++)
      if (!isNumeric(str[i])) return false;
    return true;
}
bool isHexadecimal(char ch) {
    return ((ch>='0') && (ch<='9')) ||
           ((ch>='a') && (ch<='f')) ||
           ((ch>='A') && (ch<='F'));
}
bool isAlpha(char ch) {
    return ((ch>='a') && (ch<='z')) || ((ch>='A') && (ch<='Z')) || ch=='_';
}

bool isIDString(const char *s) {
    if (!isAlpha(*s))
        return false;
    while (*s) {
        if (!(isAlpha(*s) || isNumeric(*s)))
            return false;
        s++;
    }
    return true;
}

void replace(string &str, char textFrom, const char *textTo) {
    int sLen = strlen(textTo);
    size_t p = str.find(textFrom);
    while (p != string::npos) {
        str = str.substr(0, p) + textTo + str.substr(p+1);
        p = str.find(textFrom, p+sLen);
    }
}

/// convert the given string into a quoted string suitable for javascript
std::string getJSString(const std::string &str) {
    std::string nStr = str;
    for (size_t i=0;i<nStr.size();i++) {
      const char *replaceWith = "";
      bool replace = true;

      switch (nStr[i]) {
        case '\\': replaceWith = "\\\\"; break;
        case '\n': replaceWith = "\\n"; break;
        case '"': replaceWith = "\\\""; break;
        default: replace=false;
      }

      if (replace) {
        nStr = nStr.substr(0, i) + replaceWith + nStr.substr(i+1);
        i += strlen(replaceWith)-1;
      }
    }
    return "\"" + nStr + "\"";
}

/** Is the string alphanumeric */
bool isAlphaNum(const std::string &str) {
    if (str.size()==0) return true;
    if (!isAlpha(str[0])) return false;
    for (size_t i=0;i<str.size();i++)
      if (!(isAlpha(str[i]) || isNumeric(str[i])))
        return false;
    return true;
}

// ----------------------------------------------------------------------------------- CSCRIPTEXCEPTION

CScriptException::CScriptException(const string &exceptionText) {
    text = exceptionText;
}

// ----------------------------------------------------------------------------------- CSCRIPTLEX

CScriptLex::CScriptLex(const string &input) {
    data = strdup(input.c_str());
    dataOwned = true;
    dataStart = 0;
    dataEnd = strlen(data);
    reset();
}

CScriptLex::CScriptLex(CScriptLex *owner, int startChar, int endChar) {
    data = owner->data;
    dataOwned = false;
    dataStart = startChar;
    dataEnd = endChar;
    reset();
}

CScriptLex::~CScriptLex(void)
{
    if (dataOwned)
        free((void*)data);
}

void CScriptLex::reset() {
    dataPos = dataStart;
    tokenStart = 0;
    tokenEnd = 0;
    tokenLastEnd = 0;
    tk = 0;
    tkStr = "";
    getNextCh();
    getNextCh();
    getNextToken();
}

void CScriptLex::match(int expected_tk) {
    if (tk!=expected_tk) {
        ostringstream errorString;
        errorString << "Got " << getTokenStr(tk) << " expected " << getTokenStr(expected_tk)
         << " at " << getPosition(tokenStart) << " in '" << data << "'";
        throw new CScriptException(errorString.str());
    }
    getNextToken();
}

string CScriptLex::getTokenStr(int token) {
    if (token>32 && token<128) {
        char buf[4] = "' '";
        buf[1] = token;
        return buf;
    }
    switch (token) {
        case LEX_EOF : return "EOF";
        case LEX_ID : return "ID";
        case LEX_INT : return "INT";
        case LEX_FLOAT : return "FLOAT";
        case LEX_STR : return "STRING";
        case LEX_EQUAL : return "==";
        case LEX_TYPEEQUAL : return "===";
        case LEX_NEQUAL : return "!=";
        case LEX_NTYPEEQUAL : return "!==";
        case LEX_LEQUAL : return "<=";
        case LEX_GEQUAL : return ">=";
        case LEX_PLUSEQUAL : return "+=";
        case LEX_MINUSEQUAL : return "-=";
        case LEX_PLUSPLUS : return "++";
        case LEX_MINUSMINUS : return "--";
        case LEX_ANDAND : return "&&";
        case LEX_OROR : return "||";
                // reserved words
        case LEX_R_IF : return "if";
        case LEX_R_ELSE : return "else";
        case LEX_R_WHILE : return "while";
        case LEX_R_FOR : return "for";
        case LEX_R_FUNCTION : return "function";
        case LEX_R_RETURN : return "return";
        case LEX_R_VAR : return "var";
        case LEX_R_TRUE : return "true";
        case LEX_R_FALSE : return "false";
        case LEX_R_NULL : return "null";
        case LEX_R_UNDEFINED : return "undefined";
        case LEX_R_NEW : return "new";
    }

    ostringstream msg;
    msg << "?[" << token << "]";
    return msg.str();
}

void CScriptLex::getNextCh() {
    currCh = nextCh;
    if (dataPos < dataEnd)
        nextCh = data[dataPos];
    else
        nextCh = 0;
    dataPos++;
}

void CScriptLex::getNextToken() {
    tk = LEX_EOF;
    tkStr.clear();
    while (currCh && isWhitespace(currCh)) getNextCh();
    // newline comments
    if (currCh=='/' && nextCh=='/') {
        while (currCh && currCh!='\n') getNextCh();
        getNextCh();
        getNextToken();
        return;
    }
    // block comments
    if (currCh=='/' && nextCh=='*') {
        while (currCh && (currCh!='*' || nextCh!='/')) getNextCh();
        getNextCh();
        getNextCh();
        getNextToken();
        return;
    }
    // record beginning of this token
    tokenStart = dataPos-2;
    // tokens
    if (isAlpha(currCh)) { //  IDs
        while (isAlpha(currCh) || isNumeric(currCh)) {
            tkStr += currCh;
            getNextCh();
        }
        tk = LEX_ID;
             if (tkStr=="if") tk = LEX_R_IF;
        else if (tkStr=="else") tk = LEX_R_ELSE;
        else if (tkStr=="while") tk = LEX_R_WHILE;
        else if (tkStr=="for") tk = LEX_R_FOR;
        else if (tkStr=="function") tk = LEX_R_FUNCTION;
        else if (tkStr=="return") tk = LEX_R_RETURN;
        else if (tkStr=="var") tk = LEX_R_VAR;
        else if (tkStr=="true") tk = LEX_R_TRUE;
        else if (tkStr=="false") tk = LEX_R_FALSE;
        else if (tkStr=="null") tk = LEX_R_NULL;
        else if (tkStr=="undefined") tk = LEX_R_UNDEFINED;
        else if (tkStr=="new") tk = LEX_R_NEW;
    } else if (isNumeric(currCh)) { // Numbers
        bool isHex = false;
        if (currCh=='0') { tkStr += currCh; getNextCh(); }
        if (currCh=='x') {
          isHex = true;
          tkStr += currCh; getNextCh();
        }
        tk = LEX_INT;
        while (isNumeric(currCh) || (isHex && isHexadecimal(currCh))) {
            tkStr += currCh;
            getNextCh();
        }
        if (!isHex && currCh=='.') {
            tk = LEX_FLOAT;
            tkStr += '.';
            getNextCh();
            while (isNumeric(currCh)) {
                tkStr += currCh;
                getNextCh();
            }
        }
        // do fancy e-style floating point
        if (!isHex && currCh=='e') {
          tk = LEX_FLOAT;
          tkStr += currCh; getNextCh();
          if (currCh=='-') { tkStr += currCh; getNextCh(); }
          while (isNumeric(currCh)) {
             tkStr += currCh; getNextCh();
          }
        }
    } else if (currCh=='"') {
        // strings...
        getNextCh();
        while (currCh && currCh!='"') {
            if (currCh == '\\') {
                getNextCh();
                switch (currCh) {
                case 'n' : tkStr += '\n'; break;
                case '"' : tkStr += '"'; break;
                case '\\' : tkStr += '\\'; break;
                default: tkStr += currCh;
                }
            } else {
                tkStr += currCh;
            }
            getNextCh();
        }
        getNextCh();
        tk = LEX_STR;
    } else if (currCh=='\'') {
        // strings again...
        getNextCh();
        while (currCh && currCh!='\'') {
            if (currCh == '\\') {
                getNextCh();
                switch (currCh) {
                case 'n' : tkStr += '\n'; break;
                case '\'' : tkStr += '\''; break;
                case '\\' : tkStr += '\\'; break;
                default: tkStr += currCh;
                }
            } else {
                tkStr += currCh;
            }
            getNextCh();
        }
        getNextCh();
        tk = LEX_STR;
    } else {
        // single chars
        tk = currCh;
        if (currCh) getNextCh();
        if (tk=='=' && currCh=='=') { // ==
            tk = LEX_EQUAL;
            getNextCh();
            if (currCh=='=') { // ===
              tk = LEX_TYPEEQUAL;
              getNextCh();
            }
        } else if (tk=='!' && currCh=='=') { // !=
            tk = LEX_NEQUAL;
            getNextCh();
            if (currCh=='=') { // !==
              tk = LEX_NTYPEEQUAL;
              getNextCh();
            }
        } else if (tk=='<' && currCh=='=') {
            tk = LEX_LEQUAL;
            getNextCh();
        } else if (tk=='>' && currCh=='=') {
            tk = LEX_GEQUAL;
            getNextCh();
        }  else if (tk=='+' && currCh=='=') {
            tk = LEX_PLUSEQUAL;
            getNextCh();
        }  else if (tk=='-' && currCh=='=') {
            tk = LEX_MINUSEQUAL;
            getNextCh();
        }  else if (tk=='+' && currCh=='+') {
            tk = LEX_PLUSPLUS;
            getNextCh();
        }  else if (tk=='-' && currCh=='-') {
            tk = LEX_MINUSMINUS;
            getNextCh();
        } else if (tk=='&' && currCh=='&') {
            tk = LEX_ANDAND;
            getNextCh();
        } else if (tk=='|' && currCh=='|') {
            tk = LEX_OROR;
            getNextCh();
        }
    }
    /* This isn't quite right yet */
    tokenLastEnd = tokenEnd;
    tokenEnd = dataPos-3;
}

string CScriptLex::getSubString(int lastPosition) {
    int lastCharIdx = tokenLastEnd+1;
    if (lastCharIdx < dataEnd) {
        /* save a memory alloc by using our data array to create the
           substring */
        char old = data[lastCharIdx];
        data[lastCharIdx] = 0;
        std::string value = &data[lastPosition];
        data[lastCharIdx] = old;
        return value;
    } else {
        return std::string(&data[lastPosition]);
    }
}


CScriptLex *CScriptLex::getSubLex(int lastPosition) {
    int lastCharIdx = tokenLastEnd+1;
    if (lastCharIdx < dataEnd)
        return new CScriptLex( this, lastPosition, lastCharIdx);
    else
        return new CScriptLex( this, lastPosition, dataEnd );
}

string CScriptLex::getPosition(int pos) {
    int line = 1,col = 1;
    for (int i=0;i<pos;i++) {
        char ch;
        if (i < dataEnd)
            ch = data[i];
        else
            ch = 0;
        col++;
        if (ch=='\n') {
            line++;
            col = 0;
        }
    }
    char buf[256];
    sprintf_s(buf, 256, "(line: %d, col: %d)", line, col);
    return buf;
}

// ----------------------------------------------------------------------------------- CSCRIPTVARLINK

CScriptVarLink::CScriptVarLink(CScriptVar *var, const std::string &name) {
#if DEBUG_MEMORY
    mark_allocated(this);
#endif
    this->name = name;
    this->nextSibling = 0;
    this->prevSibling = 0;
    this->var = var->ref();
    this->owned = false;
}

CScriptVarLink::~CScriptVarLink() {
#if DEBUG_MEMORY
    mark_deallocated(this);
#endif
    var->unref();
}

CScriptVarLink::CScriptVarLink(const CScriptVarLink &link) {
    // Copy constructor
#if DEBUG_MEMORY
    mark_allocated(this);
#endif
    this->name = link.name;
    this->nextSibling = 0;
    this->prevSibling = 0;
    this->var = link.var->ref();
    this->owned = false;
}

void CScriptVarLink::replaceWith(CScriptVar *newVar) {
    CScriptVar *oldVar = var;
    var = newVar->ref();
    oldVar->unref();
}

void CScriptVarLink::replaceWith(CScriptVarLink *newVar) {
    if (newVar)
      replaceWith(newVar->var);
    else
      replaceWith(new CScriptVar());
}

// ----------------------------------------------------------------------------------- CSCRIPTVAR

CScriptVar::CScriptVar() {
    refs = 0;
#if DEBUG_MEMORY
    mark_allocated(this);
#endif
    init();
    flags = SCRIPTVAR_UNDEFINED;
    data = TINYJS_BLANK_DATA;
}

CScriptVar::CScriptVar(const string &str) {
    refs = 0;
#if DEBUG_MEMORY
    mark_allocated(this);
#endif
    init();
    flags = SCRIPTVAR_STRING;
    data = str;
}


CScriptVar::CScriptVar(const string &varData, int varFlags) {
    refs = 0;
#if DEBUG_MEMORY
    mark_allocated(this);
#endif
    init();
    flags = varFlags;
    data = varData;
}

CScriptVar::CScriptVar(double val) {
    refs = 0;
#if DEBUG_MEMORY
    mark_allocated(this);
#endif
    init();
    setDouble(val);
}

CScriptVar::CScriptVar(int val) {
    refs = 0;
#if DEBUG_MEMORY
    mark_allocated(this);
#endif
    init();
    setInt(val);
}

CScriptVar::~CScriptVar(void) {
#if DEBUG_MEMORY
    mark_deallocated(this);
#endif
    removeAllChildren();
}

void CScriptVar::init() {
    firstChild = 0;
    lastChild = 0;
    flags = 0;
    jsCallback = 0;
    jsCallbackUserData = 0;
}

CScriptVar *CScriptVar::getReturnVar() {
    return getParameter(TINYJS_RETURN_VAR);
}

void CScriptVar::setReturnVar(CScriptVar *var) {
    findChildOrCreate(TINYJS_RETURN_VAR)->replaceWith(var);
}


CScriptVar *CScriptVar::getParameter(const std::string &name) {
    return findChildOrCreate(name)->var;
}

CScriptVarLink *CScriptVar::findChild(const string &childName) {
    CScriptVarLink *v = firstChild;
    while (v) {
        if (v->name.compare(childName)==0)
            return v;
        v = v->nextSibling;
    }
    return 0;
}

CScriptVarLink *CScriptVar::findChildOrCreate(const string &childName, int varFlags) {
    CScriptVarLink *l = findChild(childName);
    if (l) return l;

    return addChild(childName, new CScriptVar(TINYJS_BLANK_DATA, varFlags));
}

CScriptVarLink *CScriptVar::findChildOrCreateByPath(const std::string &path) {
  size_t p = path.find('.');
  if (p == string::npos)
    return findChildOrCreate(path);

  return findChildOrCreate(path.substr(0,p), SCRIPTVAR_OBJECT)->var->
            findChildOrCreateByPath(path.substr(p+1));
}

CScriptVarLink *CScriptVar::addChild(const std::string &childName, CScriptVar *child) {
  if (isUndefined()) {
    flags = SCRIPTVAR_OBJECT;
  }
    // if no child supplied, create one
    if (!child)
      child = new CScriptVar();

    CScriptVarLink *link = new CScriptVarLink(child, childName);
    link->owned = true;
    if (lastChild) {
        lastChild->nextSibling = link;
        link->prevSibling = lastChild;
        lastChild = link;
    } else {
        firstChild = link;
        lastChild = link;
    }
    return link;
}

CScriptVarLink *CScriptVar::addChildNoDup(const std::string &childName, CScriptVar *child) {
    // if no child supplied, create one
    if (!child)
      child = new CScriptVar();

    CScriptVarLink *v = findChild(childName);
    if (v) {
        v->replaceWith(child);
    } else {
        v = addChild(childName, child);
    }

    return v;
}

void CScriptVar::removeChild(CScriptVar *child) {
    CScriptVarLink *link = firstChild;
    while (link) {
        if (link->var == child)
            break;
        link = link->nextSibling;
    }
    ASSERT(link);
    removeLink(link);
}

void CScriptVar::removeLink(CScriptVarLink *link) {
    if (!link) return;
    if (link->nextSibling)
      link->nextSibling->prevSibling = link->prevSibling;
    if (link->prevSibling)
      link->prevSibling->nextSibling = link->nextSibling;
    if (lastChild == link)
        lastChild = link->prevSibling;
    if (firstChild == link)
        firstChild = link->nextSibling;
    delete link;
}

void CScriptVar::removeAllChildren() {
    CScriptVarLink *c = firstChild;
    while (c) {
        CScriptVarLink *t = c->nextSibling;
        delete c;
        c = t;
    }
    firstChild = 0;
    lastChild = 0;
}

CScriptVar *CScriptVar::getArrayIndex(int idx) {
    char sIdx[64];
    sprintf(sIdx, "%d", idx);
    CScriptVarLink *link = findChild(sIdx);
    if (link) return link->var;
    else return new CScriptVar(TINYJS_BLANK_DATA, SCRIPTVAR_NULL); // undefined
}

void CScriptVar::setArrayIndex(int idx, CScriptVar *value) {
    char sIdx[64];
    sprintf(sIdx, "%d", idx);
    CScriptVarLink *link = findChild(sIdx);

    if (link) {
      if (value->isUndefined())
        removeLink(link);
      else
        link->replaceWith(value);
    } else {
      if (!value->isUndefined())
        addChild(sIdx, value);
    }
}

int CScriptVar::getArrayLength() {
    int highest = -1;
    if (!isArray()) return 0;

    CScriptVarLink *link = firstChild;
    while (link) {
      if (isNumber(link->name)) {
        int val = atoi(link->name.c_str());
        if (val > highest) highest = val;
      }
      link = link->nextSibling;
    }
    return highest+1;
}

int CScriptVar::getChildren() {
    int n = 0;
    CScriptVarLink *link = firstChild;
    while (link) {
      n++;
      link = link->nextSibling;
    }
    return n;
}

int CScriptVar::getInt() {
    /* strtol understands about hex and octal */
    if (isInt()) return strtol(data.c_str(),0,0);
    if (isNull()) return 0;
    if (isUndefined()) return 0;
    if (isDouble()) return (int)getDouble();
    return 0;
}

double CScriptVar::getDouble() {
    if (isDouble()) return strtod(data.c_str(),0);
    if (isInt()) return getInt();
    if (isNull()) return 0;
    if (isUndefined()) return 0;
    return 0; /* or NaN? */
}

const string &CScriptVar::getString() {
    /* Because we can't return a string that is generated on demand.
     * I should really just use char* :) */
    static string s_null = "null";
    static string s_undefined = "undefined";
    if (isNull()) return s_null;
    if (isUndefined()) return s_undefined;
    return data;
}

void CScriptVar::setInt(int val) {
    char buf[256];
    sprintf(buf, "%d", val);
    flags = (flags&~SCRIPTVAR_VARTYPEMASK) | SCRIPTVAR_INTEGER;
    data = buf;
}

void CScriptVar::setDouble(double val) {
    char buf[256];
    sprintf(buf, "%lf", val);
    flags = (flags&~SCRIPTVAR_VARTYPEMASK) | SCRIPTVAR_DOUBLE;
    data = buf;
}

void CScriptVar::setString(const string &str) {
    // name sure it's not still a number or integer
    flags = (flags&~SCRIPTVAR_VARTYPEMASK) | SCRIPTVAR_STRING;
    data = str;
}

void CScriptVar::setUndefined() {
    // name sure it's not still a number or integer
    flags = (flags&~SCRIPTVAR_VARTYPEMASK) | SCRIPTVAR_UNDEFINED;
    data = TINYJS_BLANK_DATA;
    removeAllChildren();
}

CScriptVar *CScriptVar::mathsOp(CScriptVar *b, int op) {
    CScriptVar *a = this;
    // TODO Equality checks on classes/structures
    // Type equality check
    if (op == LEX_TYPEEQUAL || op == LEX_NTYPEEQUAL) {
      bool eql = ((a->flags & SCRIPTVAR_VARTYPEMASK) ==
                  (b->flags & SCRIPTVAR_VARTYPEMASK)) &&
                 a->data == b->data;
      if (op == LEX_TYPEEQUAL)
        return new CScriptVar(eql);
      else
        return new CScriptVar(!eql);
    }
    // do maths...
    if (a->isUndefined() && b->isUndefined()) {
      if (op == LEX_EQUAL) return new CScriptVar(true);
      else if (op == LEX_NEQUAL) return new CScriptVar(false);
      else return new CScriptVar(); // undefined
    } else if ((a->isNumeric() || a->isUndefined()) &&
               (b->isNumeric() || b->isUndefined())) {
        if (!a->isDouble() && !b->isDouble()) {
            // use ints
            int da = a->getInt();
            int db = b->getInt();
            switch (op) {
                case '+': return new CScriptVar(da+db);
                case '-': return new CScriptVar(da-db);
                case '*': return new CScriptVar(da*db);
                case '/': return new CScriptVar(da/db);
                case '&': return new CScriptVar(da&db);
                case '|': return new CScriptVar(da|db);
                case '^': return new CScriptVar(da^db);
                case '%': return new CScriptVar(da%db);
                case LEX_EQUAL:     return new CScriptVar(da==db);
                case LEX_NEQUAL:    return new CScriptVar(da!=db);
                case '<':     return new CScriptVar(da<db);
                case LEX_LEQUAL:    return new CScriptVar(da<=db);
                case '>':     return new CScriptVar(da>db);
                case LEX_GEQUAL:    return new CScriptVar(da>=db);
                default: throw new CScriptException("This operation not supported on the int datatype");
            }
        } else {
            // use doubles
            double da = a->getDouble();
            double db = b->getDouble();
            switch (op) {
                case '+': return new CScriptVar(da+db);
                case '-': return new CScriptVar(da-db);
                case '*': return new CScriptVar(da*db);
                case '/': return new CScriptVar(da/db);
                case LEX_EQUAL:     return new CScriptVar(da==db);
                case LEX_NEQUAL:    return new CScriptVar(da!=db);
                case '<':     return new CScriptVar(da<db);
                case LEX_LEQUAL:    return new CScriptVar(da<=db);
                case '>':     return new CScriptVar(da>db);
                case LEX_GEQUAL:    return new CScriptVar(da>=db);
                default: throw new CScriptException("This operation not supported on the double datatype");
            }
        }
    } else {
       string da = a->getString();
       string db = b->getString();
       // use strings
       switch (op) {
           case '+':           return new CScriptVar(da+db, SCRIPTVAR_STRING);
           case LEX_EQUAL:     return new CScriptVar(da==db);
           case LEX_NEQUAL:    return new CScriptVar(da!=db);
           case '<':     return new CScriptVar(da<db);
           case LEX_LEQUAL:    return new CScriptVar(da<=db);
           case '>':     return new CScriptVar(da>db);
           case LEX_GEQUAL:    return new CScriptVar(da>=db);
           default: throw new CScriptException("This operation not supported on the string datatype");
       }
    }
    ASSERT(0);
    return 0;
}

void CScriptVar::copyValue(CScriptVar *val) {
    if (val) {
      // we *don't* copy the name
      data = val->data;
      flags = (flags & ~SCRIPTVAR_VARTYPEMASK) | (val->flags & SCRIPTVAR_VARTYPEMASK);
      // remove all current children
      removeAllChildren();
      // copy children of 'val'
      CScriptVarLink *child = val->firstChild;
      while (child) {
        CScriptVar *copied;
        // don't copy the 'parent' object...
        if (child->name != TINYJS_PROTOTYPE_CLASS)
          copied = child->var->deepCopy();
        else
          copied = child->var;

        addChild(child->name, copied);

        child = child->nextSibling;
      }
    } else {
      setUndefined();
    }
}

CScriptVar *CScriptVar::deepCopy() {
    CScriptVar *newVar = new CScriptVar(data, flags);
    // copy children
    CScriptVarLink *child = firstChild;
    while (child) {
        CScriptVar *copied;
        // don't copy the 'parent' object...
        if (child->name != TINYJS_PROTOTYPE_CLASS)
          copied = child->var->deepCopy();
        else
          copied = child->var;

        newVar->addChild(child->name, copied);
        child = child->nextSibling;
    }
    return newVar;
}

void CScriptVar::trace(string indentStr, const string &name) {
    TRACE("%s'%s' = '%s' %s\n",
        indentStr.c_str(),
        name.c_str(),
        data.c_str(),
        getFlagsAsString().c_str());
    string indent = indentStr+" ";
    CScriptVarLink *link = firstChild;
    while (link) {
      link->var->trace(indent, link->name);
      link = link->nextSibling;
    }
}

string CScriptVar::getFlagsAsString() {
  string flagstr = "";
  if (flags&SCRIPTVAR_FUNCTION) flagstr = flagstr + "FUNCTION ";
  if (flags&SCRIPTVAR_OBJECT) flagstr = flagstr + "OBJECT ";
  if (flags&SCRIPTVAR_ARRAY) flagstr = flagstr + "ARRAY ";
  if (flags&SCRIPTVAR_NATIVE) flagstr = flagstr + "NATIVE ";
  if (flags&SCRIPTVAR_DOUBLE) flagstr = flagstr + "DOUBLE ";
  if (flags&SCRIPTVAR_INTEGER) flagstr = flagstr + "INTEGER ";
  if (flags&SCRIPTVAR_STRING) flagstr = flagstr + "STRING ";
  return flagstr;
}

string CScriptVar::getParsableString() {
  // Numbers can just be put in directly
  if (isNumeric())
    return getString();
  if (isFunction()) {
    ostringstream funcStr;
    funcStr << "function (";
    // get list of parameters
    CScriptVarLink *link = firstChild;
    while (link) {
      funcStr << link->name;
      if (link->nextSibling) funcStr << ",";
      link = link->nextSibling;
    }
    // add function body
    funcStr << ") " << getString();
    return funcStr.str();
  }
  // if it is a string then we quote it
  if (isString())
    return getJSString(getString());
  if (isNull())
      return "null";
  return "undefined";
}

void CScriptVar::getJSON(ostringstream &destination, const string linePrefix) {
   if (isObject()) {
      string indentedLinePrefix = linePrefix+"  ";
      // children - handle with bracketed list
      destination << "{ \n";
      CScriptVarLink *link = firstChild;
      while (link) {
        destination << indentedLinePrefix;
        if (isAlphaNum(link->name))
          destination  << link->name;
        else
          destination  << getJSString(link->name);
        destination  << " : ";
        link->var->getJSON(destination, indentedLinePrefix);
        link = link->nextSibling;
        if (link) {
          destination  << ",\n";
        }
      }
      destination << "\n" << linePrefix << "}";
    } else if (isArray()) {
      string indentedLinePrefix = linePrefix+"  ";
      destination << "[\n";
      int len = getArrayLength();
      if (len>10000) len=10000; // we don't want to get stuck here!

      for (int i=0;i<len;i++) {
        getArrayIndex(i)->getJSON(destination, indentedLinePrefix);
        if (i<len-1) destination  << ",\n";
      }

      destination << "\n" << linePrefix << "]";
    } else {
      // no children or a function... just write value directly
      destination << getParsableString();
    }
}


void CScriptVar::setCallback(JSCallback callback, void *userdata) {
    jsCallback = callback;
    jsCallbackUserData = userdata;
}

CScriptVar *CScriptVar::ref() {
    refs++;
    return this;
}

void CScriptVar::unref() {
    if (refs<=0) printf("OMFG, we have unreffed too far!\n");
    if ((--refs)==0) {
      delete this;
    }
}

int CScriptVar::getRefs() {
    return refs;
}


// ----------------------------------------------------------------------------------- CSCRIPT

CTinyJS::CTinyJS() {
    l = 0;
    root = (new CScriptVar(TINYJS_BLANK_DATA, SCRIPTVAR_OBJECT))->ref();
    // Add built-in classes
    stringClass = (new CScriptVar(TINYJS_BLANK_DATA, SCRIPTVAR_OBJECT))->ref();
    arrayClass = (new CScriptVar(TINYJS_BLANK_DATA, SCRIPTVAR_OBJECT))->ref();
    objectClass = (new CScriptVar(TINYJS_BLANK_DATA, SCRIPTVAR_OBJECT))->ref();
    root->addChild("String", stringClass);
    root->addChild("Array", arrayClass);
    root->addChild("Object", objectClass);
}

CTinyJS::~CTinyJS() {
    ASSERT(!l);
    scopes.clear();
    stringClass->unref();
    objectClass->unref();
    root->unref();

#if DEBUG_MEMORY
    show_allocated();
#endif
}

void CTinyJS::trace() {
    root->trace();
}

void CTinyJS::execute(const string &code) {
    CScriptLex *oldLex = l;
    vector<CScriptVar*> oldScopes = scopes;
    l = new CScriptLex(code);
    scopes.clear();
    scopes.push_back(root);
    try {
        bool execute = true;
        while (l->tk) statement(execute);
    } catch (CScriptException *e) {
        ostringstream msg;
        msg << "Error " << e->text << " at " << l->getPosition(l->tokenLastEnd);
        delete l;
        l = oldLex;
        throw new CScriptException(msg.str());
    }
    delete l;
    l = oldLex;
    scopes = oldScopes;
}

CScriptVarLink CTinyJS::evaluateComplex(const string &code) {
    CScriptLex *oldLex = l;
    vector<CScriptVar*> oldScopes = scopes;

    l = new CScriptLex(code);
    scopes.clear();
    scopes.push_back(root);
    CScriptVarLink *v = 0;
    try {
        bool execute = true;
        v = base(execute);
    } catch (CScriptException *e) {
        ostringstream msg;
        msg << "Error " << e->text << " at " << l->getPosition(l->tokenLastEnd);
        delete l;
        l = oldLex;
        throw new CScriptException(msg.str());
    }
    delete l;
    l = oldLex;
    scopes = oldScopes;

    if (v) return *v;
    // return undefined...
    return CScriptVarLink(new CScriptVar());
}

string CTinyJS::evaluate(const string &code) {
    return evaluateComplex(code).var->getString();
}

void CTinyJS::parseFunctionArguments(CScriptVar *funcVar) {
  l->match('(');
  while (l->tk!=')') {
      funcVar->addChildNoDup(l->tkStr);
      l->match(LEX_ID);
      if (l->tk!=')') l->match(',');
  }
  l->match(')');
}

void CTinyJS::addNative(const string &funcDesc, JSCallback ptr, void *userdata) {
    CScriptLex *oldLex = l;
    l = new CScriptLex(funcDesc);

    CScriptVar *base = root;

    l->match(LEX_R_FUNCTION);
    string funcName = l->tkStr;
    l->match(LEX_ID);
    /* Check for dots, we might want to do something like function String.substring ... */
    while (l->tk == '.') {
      l->match('.');
      CScriptVarLink *link = base->findChild(funcName);
      // if it doesn't exist, make an object class
      if (!link) link = base->addChild(funcName, new CScriptVar(TINYJS_BLANK_DATA, SCRIPTVAR_OBJECT));
      base = link->var;
      funcName = l->tkStr;
      l->match(LEX_ID);
    }

    CScriptVar *funcVar = new CScriptVar(TINYJS_BLANK_DATA, SCRIPTVAR_FUNCTION | SCRIPTVAR_NATIVE);
    funcVar->setCallback(ptr, userdata);
    parseFunctionArguments(funcVar);
    delete l;
    l = oldLex;

    base->addChild(funcName, funcVar);
}

CScriptVarLink *CTinyJS::parseFunctionDefinition() {
  // actually parse a function...
  l->match(LEX_R_FUNCTION);
  string funcName = TINYJS_TEMP_NAME;
  /* we can have functions without names */
  if (l->tk==LEX_ID) {
    funcName = l->tkStr;
    l->match(LEX_ID);
  }
  CScriptVarLink *funcVar = new CScriptVarLink(new CScriptVar(TINYJS_BLANK_DATA, SCRIPTVAR_FUNCTION), funcName);
  parseFunctionArguments(funcVar->var);
  int funcBegin = l->tokenStart;
  bool noexecute = false;
  block(noexecute);
  funcVar->var->data = l->getSubString(funcBegin);
  return funcVar;
}

CScriptVarLink *CTinyJS::factor(bool &execute) {
    if (l->tk=='(') {
        l->match('(');
        CScriptVarLink *a = base(execute);
        l->match(')');
        return a;
    }
    if (l->tk==LEX_R_TRUE) {
        l->match(LEX_R_TRUE);
        return new CScriptVarLink(new CScriptVar(1));
    }
    if (l->tk==LEX_R_FALSE) {
        l->match(LEX_R_FALSE);
        return new CScriptVarLink(new CScriptVar(0));
    }
    if (l->tk==LEX_R_NULL) {
        l->match(LEX_R_NULL);
        return new CScriptVarLink(new CScriptVar(TINYJS_BLANK_DATA,SCRIPTVAR_NULL));
    }
    if (l->tk==LEX_R_UNDEFINED) {
        l->match(LEX_R_UNDEFINED);
        return new CScriptVarLink(new CScriptVar(TINYJS_BLANK_DATA,SCRIPTVAR_UNDEFINED));
    }
    if (l->tk==LEX_ID) {
        CScriptVarLink *a = execute ? findInScopes(l->tkStr) : new CScriptVarLink(new CScriptVar());
        /* The parent if we're executing a method call */
        CScriptVar *parent = 0;

        if (execute && !a) {
          /* Variable doesn't exist! JavaScript says we should create it
           * (we won't add it here. This is done in the assignment operator)*/
          a = new CScriptVarLink(new CScriptVar(), l->tkStr);
        }
        l->match(LEX_ID);
        while (l->tk=='(' || l->tk=='.' || l->tk=='[') {
            if (l->tk=='(') { // ------------------------------------- Function Call
              if (execute) {
                if (!a->var->isFunction()) {
                    string errorMsg = "Expecting '";
                    errorMsg = errorMsg + a->name + "' to be a function";
                    throw new CScriptException(errorMsg.c_str());
                }
                l->match('(');
                // create a new symbol table entry for execution of this function
                CScriptVar *functionRoot = new CScriptVar(TINYJS_BLANK_DATA, SCRIPTVAR_FUNCTION);
                if (parent)
                  functionRoot->addChildNoDup("this", parent);
                // grab in all parameters
                CScriptVarLink *v = a->var->firstChild;
                while (v) {
                    CScriptVarLink *value = base(execute);
                    if (execute) {
                        if (value->var->isBasic()) {
                          // pass by value
                          functionRoot->addChild(v->name, value->var->deepCopy());
                        } else {
                          // pass by reference
                          functionRoot->addChild(v->name, value->var);
                        }
                    }
                    CLEAN(value);
                    if (l->tk!=')') l->match(',');
                    v = v->nextSibling;
                }
                l->match(')');
                // setup a return variable
                CScriptVarLink *returnVar = NULL;
                // execute function!
                // add the function's execute space to the symbol table so we can recurse
                CScriptVarLink *returnVarLink = functionRoot->addChild(TINYJS_RETURN_VAR);
                scopes.push_back(functionRoot);

                if (a->var->isNative()) {
                    ASSERT(a->var->jsCallback);
                    a->var->jsCallback(functionRoot, a->var->jsCallbackUserData);
                } else {
                    /* we just want to execute the block, but something could
                     * have messed up and left us with the wrong ScriptLex, so
                     * we want to be careful here... */
                    CScriptException *exception = 0;
                    CScriptLex *oldLex = l;
                    CScriptLex *newLex = new CScriptLex(a->var->getString());
                    l = newLex;
                    try {
                      block(execute);
                      // because return will probably have called this, and set execute to false
                      execute = true;
                    } catch (CScriptException *e) {
                      exception = e;
                    }
                    delete newLex;
                    l = oldLex;

                    if (exception)
                      throw exception;
                }

                scopes.pop_back();
                /* get the real return var before we remove it from our function */
                returnVar = new CScriptVarLink(returnVarLink->var);
                functionRoot->removeLink(returnVarLink);
                delete functionRoot;
                if (returnVar)
                  a = returnVar;
                else
                  a = new CScriptVarLink(new CScriptVar());
              } else {
                // function, but not executing - just parse args and be done
                l->match('(');
                while (l->tk != ')') {
                  CScriptVarLink *value = base(execute);
                  CLEAN(value);
                  if (l->tk!=')') l->match(',');
                }
                l->match(')');
                if (l->tk == '{') {
                  block(execute);
                }
              }
            } else if (l->tk == '.') { // ------------------------------------- Record Access
                l->match('.');
                if (execute) {
                  const string &name = l->tkStr;
                  CScriptVarLink *child = a->var->findChild(name);
                  if (!child) child = findInParentClasses(a->var, name);
                  if (!child) {
                    /* if we haven't found this defined yet, use the built-in
                       'length' properly */
                    if (a->var->isArray() && name == "length") {
                      int l = a->var->getArrayLength();
                      child = new CScriptVarLink(new CScriptVar(l));
                    } else if (a->var->isString() && name == "length") {
                      int l = a->var->getString().size();
                      child = new CScriptVarLink(new CScriptVar(l));
                    } else {
                      child = a->var->addChild(name);
                    }
                  }
                  parent = a->var;
                  a = child;
                }
                l->match(LEX_ID);
            } else if (l->tk == '[') { // ------------------------------------- Array Access
                l->match('[');
                CScriptVarLink *index = expression(execute);
                l->match(']');
                if (execute) {
                  CScriptVarLink *child = a->var->findChildOrCreate(index->var->getString());
                  parent = a->var;
                  a = child;
                }
                CLEAN(index);
            } else ASSERT(0);
        }
        return a;
    }
    if (l->tk==LEX_INT || l->tk==LEX_FLOAT) {
        CScriptVar *a = new CScriptVar(l->tkStr,
            ((l->tk==LEX_INT)?SCRIPTVAR_INTEGER:SCRIPTVAR_DOUBLE));
        l->match(l->tk);
        return new CScriptVarLink(a);
    }
    if (l->tk==LEX_STR) {
        CScriptVar *a = new CScriptVar(l->tkStr, SCRIPTVAR_STRING);
        l->match(LEX_STR);
        return new CScriptVarLink(a);
    }
    if (l->tk=='{') {
        CScriptVar *contents = new CScriptVar(TINYJS_BLANK_DATA, SCRIPTVAR_OBJECT);
        /* JSON-style object definition */
        l->match('{');
        while (l->tk != '}') {
          string id = l->tkStr;
          // we only allow strings or IDs on the left hand side of an initialisation
          if (l->tk==LEX_STR) l->match(LEX_STR);
          else l->match(LEX_ID);
          l->match(':');
          if (execute) {
            CScriptVarLink *a = base(execute);
            contents->addChild(id, a->var);
            CLEAN(a);
          }
          // no need to clean here, as it will definitely be used
          if (l->tk != '}') l->match(',');
        }

        l->match('}');
        return new CScriptVarLink(contents);
    }
    if (l->tk=='[') {
        CScriptVar *contents = new CScriptVar(TINYJS_BLANK_DATA, SCRIPTVAR_ARRAY);
        /* JSON-style array */
        l->match('[');
        int idx = 0;
        while (l->tk != ']') {
          if (execute) {
            char idx_str[16]; // big enough for 2^32
            sprintf(idx_str,"%d",idx);

            CScriptVarLink *a = base(execute);
            contents->addChild(idx_str, a->var);
            CLEAN(a);
          }
          // no need to clean here, as it will definitely be used
          if (l->tk != ']') l->match(',');
          idx++;
        }
        l->match(']');
        return new CScriptVarLink(contents);
    }
    if (l->tk==LEX_R_FUNCTION) {
      CScriptVarLink *funcVar = parseFunctionDefinition();
        if (funcVar->name != TINYJS_TEMP_NAME)
          TRACE("Functions not defined at statement-level are not meant to have a name");
        return funcVar;
    }
    if (l->tk==LEX_R_NEW) {
      // new -> create a new object
      l->match(LEX_R_NEW);
      const string &className = l->tkStr;
      if (execute) {
        CScriptVarLink *objClass = findInScopes(className);
        if (!objClass) {
          TRACE("%s is not a valid class name", className.c_str());
          return new CScriptVarLink(new CScriptVar());
        }
        l->match(LEX_ID);
        CScriptVar *obj = new CScriptVar(TINYJS_BLANK_DATA, SCRIPTVAR_OBJECT);
        obj->addChild(TINYJS_PROTOTYPE_CLASS, objClass->var);
        if (l->tk == '(') {
          l->match('(');
          l->match(')');
        }
        // TODO: Object constructors
        return new CScriptVarLink(obj);
      } else {
        l->match(LEX_ID);
        if (l->tk == '(') {
          l->match('(');
          l->match(')');
        }
      }
    }
    // Nothing we can do here... just hope it's the end...
    l->match(LEX_EOF);
    return 0;
}

CScriptVarLink *CTinyJS::unary(bool &execute) {
    CScriptVarLink *a;
    if (l->tk=='!') {
        l->match('!'); // binary not
        a = factor(execute);
        if (execute) {
            CScriptVar zero(0);
            CScriptVar *res = a->var->mathsOp(&zero, LEX_EQUAL);
            CREATE_LINK(a, res);
        }
    } else
        a = factor(execute);
    return a;
}

CScriptVarLink *CTinyJS::term(bool &execute) {
    CScriptVarLink *a = unary(execute);
    while (l->tk=='*' || l->tk=='/' || l->tk=='%') {
        int op = l->tk;
        l->match(l->tk);
        CScriptVarLink *b = unary(execute);
        if (execute) {
            CScriptVar *res = a->var->mathsOp(b->var, op);
            CREATE_LINK(a, res);
        }
        CLEAN(b);
    }
    return a;
}

CScriptVarLink *CTinyJS::expression(bool &execute) {
    bool negate = false;
    if (l->tk=='-') {
        l->match('-');
        negate = true;
    }
    CScriptVarLink *a = term(execute);
    if (negate) {
        CScriptVar *zero = new CScriptVar(0);
        CScriptVar *res = zero->mathsOp(a->var, '-');
        CREATE_LINK(a, res);
    }

    while (l->tk=='+' || l->tk=='-' ||
        l->tk==LEX_PLUSPLUS || l->tk==LEX_MINUSMINUS) {
        int op = l->tk;
        l->match(l->tk);
        if (op==LEX_PLUSPLUS || op==LEX_MINUSMINUS) {
            if (execute) {
                CScriptVar one(1);
                CScriptVar *res = a->var->mathsOp(&one, op==LEX_PLUSPLUS ? '+' : '-');
                // in-place add/subtract
                a->replaceWith(res);
            }
        } else {
            CScriptVarLink *b = term(execute);
            if (execute) {
                // not in-place, so just replace
                CScriptVar *res = a->var->mathsOp(b->var, op);
                CREATE_LINK(a, res);
            }
            CLEAN(b);
        }
    }
    return a;
}

CScriptVarLink *CTinyJS::condition(bool &execute) {
    CScriptVarLink *a = expression(execute);
    CScriptVarLink *b;
    while (l->tk==LEX_EQUAL || l->tk==LEX_NEQUAL ||
           l->tk==LEX_TYPEEQUAL || l->tk==LEX_NTYPEEQUAL ||
           l->tk==LEX_LEQUAL || l->tk==LEX_GEQUAL ||
           l->tk=='<' || l->tk=='>') {
        int op = l->tk;
        l->match(l->tk);
        b = expression(execute);
        if (execute) {
            CScriptVar *res = a->var->mathsOp(b->var, op);
            CREATE_LINK(a,res);
        }
        CLEAN(b);
    }
    return a;
}

CScriptVarLink *CTinyJS::logic(bool &execute) {
    CScriptVarLink *a = condition(execute);
    CScriptVarLink *b;
    while (l->tk=='&' || l->tk=='|' || l->tk=='^' || l->tk==LEX_ANDAND || l->tk==LEX_OROR) {
        bool noexecute = false;
        int op = l->tk;
        l->match(l->tk);
        bool shortCircuit = false;
        bool boolean = false;
        // if we have short-circuit ops, then if we know the outcome
        // we don't bother to execute the other op. Even if not
        // we need to tell mathsOp it's an & or |
        if (op==LEX_ANDAND) {
            op = '&';
            shortCircuit = !a->var->getBool();
            boolean = true;
        } else if (op==LEX_OROR) {
            op = '|';
            shortCircuit = a->var->getBool();
            boolean = true;
        }
        b = condition(shortCircuit ? noexecute : execute);
        if (execute && !shortCircuit) {
            if (boolean) {
              CScriptVar *newa = new CScriptVar(a->var->getBool());
              CScriptVar *newb = new CScriptVar(b->var->getBool());
              CREATE_LINK(a, newa);
              CREATE_LINK(b, newb);
            }
            CScriptVar *res = a->var->mathsOp(b->var, op);
            CREATE_LINK(a, res);
        }
        CLEAN(b);
    }
    return a;
}

CScriptVarLink *CTinyJS::base(bool &execute) {
    CScriptVarLink *lhs = logic(execute);
    if (l->tk=='=' || l->tk==LEX_PLUSEQUAL || l->tk==LEX_MINUSEQUAL) {
        /* If we're assigning to this and we don't have a parent,
         * add it to the symbol table root as per JavaScript. */
        if (execute && !lhs->owned) {
          if (lhs->name.length()>0) {
            CScriptVarLink *realLhs = root->addChildNoDup(lhs->name, lhs->var);
            CLEAN(lhs);
            lhs = realLhs;
          } else
            TRACE("Trying to assign to an un-named type\n");
        }

        int op = l->tk;
        l->match(l->tk);
        CScriptVarLink *rhs = base(execute);
        if (execute) {
            if (op=='=') {
                lhs->replaceWith(rhs);
            } else if (op==LEX_PLUSEQUAL) {
                CScriptVar *res = lhs->var->mathsOp(rhs->var, '+');
                lhs->replaceWith(res);
            } else if (op==LEX_MINUSEQUAL) {
                CScriptVar *res = lhs->var->mathsOp(rhs->var, '-');
                lhs->replaceWith(res);
            } else ASSERT(0);
        }
        CLEAN(rhs);
    }
    return lhs;
}

void CTinyJS::block(bool &execute) {
    // TODO: fast skip of blocks
    l->match('{');
    if (execute) {
      while (l->tk && l->tk!='}')
        statement(execute);
      l->match('}');
    } else {
      int brackets = 1;
      while (l->tk && brackets) {
        if (l->tk == '{') brackets++;
        if (l->tk == '}') brackets--;
        l->match(l->tk);
      }
    }

}

void CTinyJS::statement(bool &execute) {
    if (l->tk==LEX_ID ||
        l->tk==LEX_INT ||
        l->tk==LEX_FLOAT ||
        l->tk==LEX_STR ||
        l->tk=='-') {
        /* Execute a simple statement that only contains basic arithmetic... */
        CLEAN(base(execute));
        l->match(';');
    } else if (l->tk=='{') {
        /* A block of code */
        block(execute);
    } else if (l->tk==';') {
        /* Empty statement - to allow things like ;;; */
        l->match(';');
    } else if (l->tk==LEX_R_VAR) {
        /* variable creation. TODO - we need a better way of parsing the left
         * hand side. Maybe just have a flag called can_create_var that we
         * set and then we parse as if we're doing a normal equals.*/
        l->match(LEX_R_VAR);
        CScriptVarLink *a = 0;
        if (execute)
          a = scopes.back()->findChildOrCreate(l->tkStr);
        l->match(LEX_ID);
        // now do stuff defined with dots
        while (l->tk == '.') {
            l->match('.');
            if (execute) {
                CScriptVarLink *lastA = a;
                a = lastA->var->findChildOrCreate(l->tkStr);
            }
            l->match(LEX_ID);
        }
        // sort out initialiser
        if (l->tk == '=') {
            l->match('=');
            CScriptVarLink *var = base(execute);
            if (execute)
                a->replaceWith(var);
            CLEAN(var);
        }
        l->match(';');
    } else if (l->tk==LEX_R_IF) {
        l->match(LEX_R_IF);
        l->match('(');
        CScriptVarLink *var = base(execute);
        l->match(')');
        bool cond = execute && var->var->getBool();
        CLEAN(var);
        bool noexecute = false; // because we need to be abl;e to write to it
        statement(cond ? execute : noexecute);
        if (l->tk==LEX_R_ELSE) {
            l->match(LEX_R_ELSE);
            statement(cond ? noexecute : execute);
        }
    } else if (l->tk==LEX_R_WHILE) {
        // We do repetition by pulling out the string representing our statement
        // there's definitely some opportunity for optimisation here
        l->match(LEX_R_WHILE);
        l->match('(');
        int whileCondStart = l->tokenStart;
        bool noexecute = false;
        CScriptVarLink *cond = base(execute);
        bool loopCond = execute && cond->var->getBool();
        CLEAN(cond);
        CScriptLex *whileCond = l->getSubLex(whileCondStart);
        l->match(')');
        int whileBodyStart = l->tokenStart;
        statement(loopCond ? execute : noexecute);
        CScriptLex *whileBody = l->getSubLex(whileBodyStart);
        CScriptLex *oldLex = l;
        int loopCount = TINYJS_LOOP_MAX_ITERATIONS;
        while (loopCond && loopCount-->0) {
            whileCond->reset();
            l = whileCond;
            cond = base(execute);
            loopCond = execute && cond->var->getBool();
            CLEAN(cond);
            if (loopCond) {
                whileBody->reset();
                l = whileBody;
                statement(execute);
            }
        }
        l = oldLex;
        delete whileCond;
        delete whileBody;

        if (loopCount<=0) {
            root->trace();
            TRACE("WHILE Loop exceeded %d iterations at %s\n", TINYJS_LOOP_MAX_ITERATIONS, l->getPosition(l->tokenLastEnd).c_str());
            throw new CScriptException("LOOP_ERROR");
        }
    } else if (l->tk==LEX_R_FOR) {
        l->match(LEX_R_FOR);
        l->match('(');
        statement(execute); // initialisation
        //l->match(';');
        int forCondStart = l->tokenStart;
        bool noexecute = false;
        CScriptVarLink *cond = base(execute); // condition
        bool loopCond = execute && cond->var->getBool();
        CLEAN(cond);
        CScriptLex *forCond = l->getSubLex(forCondStart);
        l->match(';');
        int forIterStart = l->tokenStart;
        base(noexecute); // iterator
        CScriptLex *forIter = l->getSubLex(forIterStart);
        l->match(')');
        int forBodyStart = l->tokenStart;
        statement(loopCond ? execute : noexecute);
        CScriptLex *forBody = l->getSubLex(forBodyStart);
        CScriptLex *oldLex = l;
        if (loopCond) {
            forIter->reset();
            l = forIter;
            base(execute);
        }
        int loopCount = TINYJS_LOOP_MAX_ITERATIONS;
        while (execute && loopCond && loopCount-->0) {
            forCond->reset();
            l = forCond;
            cond = base(execute);
            loopCond = cond->var->getBool();
            CLEAN(cond);
            if (execute && loopCond) {
                forBody->reset();
                l = forBody;
                statement(execute);
            }
            if (execute && loopCond) {
                forIter->reset();
                l = forIter;
                base(execute);
            }
        }
        l = oldLex;
        delete forCond;
        delete forIter;
        delete forBody;
        if (loopCount<=0) {
            root->trace();
            TRACE("FOR Loop exceeded %d iterations at %s\n", TINYJS_LOOP_MAX_ITERATIONS, l->getPosition(l->tokenLastEnd).c_str());
            throw new CScriptException("LOOP_ERROR");
        }
    } else if (l->tk==LEX_R_RETURN) {
        l->match(LEX_R_RETURN);
        CScriptVarLink *result = 0;
        if (l->tk != ';')
          result = base(execute);
        if (execute) {
          CScriptVarLink *resultVar = scopes.back()->findChild(TINYJS_RETURN_VAR);
          if (resultVar)
            resultVar->replaceWith(result);
          else
            TRACE("RETURN statement, but not in a function.\n");
          execute = false;
        }
        CLEAN(result);
        l->match(';');
    } else if (l->tk==LEX_R_FUNCTION) {
        CScriptVarLink *funcVar = parseFunctionDefinition();
        if (execute) {
          if (funcVar->name == TINYJS_TEMP_NAME)
            TRACE("Functions defined at statement-level are meant to have a name\n");
          else
            scopes.back()->addChildNoDup(funcVar->name, funcVar->var);
        }
        CLEAN(funcVar);
    } else l->match(LEX_EOF);
}

/// Get the value of the given variable, or return 0
const string *CTinyJS::getVariable(const string &path) {
    // traverse path
    size_t prevIdx = 0;
    size_t thisIdx = path.find('.');
    if (thisIdx == string::npos) thisIdx = path.length();
    CScriptVar *var = root;
    while (var && prevIdx<path.length()) {
        string el = path.substr(prevIdx, thisIdx-prevIdx);
        CScriptVarLink *varl = var->findChild(el);
        var = varl?varl->var:0;
        prevIdx = thisIdx+1;
        thisIdx = path.find('.', prevIdx);
        if (thisIdx == string::npos) thisIdx = path.length();
    }
    // return result
    if (var)
        return &var->getString();
    else
        return 0;
}

/// Finds a child, looking recursively up the scopes
CScriptVarLink *CTinyJS::findInScopes(const std::string &childName) {
    for (int s=scopes.size()-1;s>=0;s--) {
      CScriptVarLink *v = scopes[s]->findChild(childName);
      if (v) return v;
    }
    return NULL;

}

/// Look up in any parent classes of the given object
CScriptVarLink *CTinyJS::findInParentClasses(CScriptVar *object, const std::string &name) {
    // Look for links to actual parent classes
    CScriptVarLink *parentClass = object->findChild(TINYJS_PROTOTYPE_CLASS);
    while (parentClass) {
      CScriptVarLink *implementation = parentClass->var->findChild(name);
      if (implementation) return implementation;
      parentClass = parentClass->var->findChild(TINYJS_PROTOTYPE_CLASS);
    }
    // else fake it for strings and finally objects
    if (object->isString()) {
      CScriptVarLink *implementation = stringClass->findChild(name);
      if (implementation) return implementation;
    }
    if (object->isArray()) {
      CScriptVarLink *implementation = arrayClass->findChild(name);
      if (implementation) return implementation;
    }
    CScriptVarLink *implementation = objectClass->findChild(name);
    if (implementation) return implementation;

    return 0;
}