// This file is distributed under the BSD License.
// See "license.txt" for details.
// Copyright 2009-2010, Jonathan Turner (jonathan@emptycrate.com)
// and Jason Turner (jason@emptycrate.com)
// http://www.chaiscript.com

#ifndef CHAISCRIPT_PARSER_HPP_
#define CHAISCRIPT_PARSER_HPP_

#include <boost/assign/std/vector.hpp>

#include <exception>
#include <fstream>
#include <sstream>

#include "chaiscript_prelude.hpp"
#include "chaiscript_common.hpp"

namespace chaiscript
{
  class ChaiScript_Parser {

    std::string::const_iterator input_pos, input_end;
    int line, col;
    std::string multiline_comment_begin, multiline_comment_end;
    std::string singleline_comment;
    const char *filename;
    std::vector<AST_NodePtr> match_stack;

    std::vector<std::vector<std::string> > operator_matches;
    std::vector<AST_Node_Type::Type> operators;

  public:
    ChaiScript_Parser() {           
      multiline_comment_begin = "/*";
      multiline_comment_end = "*/";
      singleline_comment = "//";

      setup_operators();
    }

    ChaiScript_Parser(const ChaiScript_Parser &); // explicitly unimplemented copy constructor
    ChaiScript_Parser &operator=(const ChaiScript_Parser &); // explicitly unimplemented assignment operator

    void setup_operators() {
      using namespace boost::assign;
                        
      operators.push_back(AST_Node_Type::Logical_Or);
      std::vector<std::string> logical_or;
      logical_or += "||";
      operator_matches.push_back(logical_or);

      operators.push_back(AST_Node_Type::Logical_And);
      std::vector<std::string> logical_and;
      logical_and += "&&";
      operator_matches.push_back(logical_and);

      operators.push_back(AST_Node_Type::Bitwise_Or);
      std::vector<std::string> bitwise_or;
      bitwise_or += "|";
      operator_matches.push_back(bitwise_or);

      operators.push_back(AST_Node_Type::Bitwise_Xor);
      std::vector<std::string> bitwise_xor;
      bitwise_xor += "^";
      operator_matches.push_back(bitwise_xor);           

      operators.push_back(AST_Node_Type::Bitwise_And);
      std::vector<std::string> bitwise_and;
      bitwise_and += "&";
      operator_matches.push_back(bitwise_and);

      operators.push_back(AST_Node_Type::Equality);
      std::vector<std::string> equality;
      equality += "==", "!=";
      operator_matches.push_back(equality);           

      operators.push_back(AST_Node_Type::Comparison);
      std::vector<std::string> comparison;
      comparison += "<", "<=", ">", ">=";
      operator_matches.push_back(comparison);

      operators.push_back(AST_Node_Type::Shift);
      std::vector<std::string> shift;
      shift += "<<", ">>";
      operator_matches.push_back(shift);           

      operators.push_back(AST_Node_Type::Additive);
      std::vector<std::string> additive;
      additive += "+", "-";
      operator_matches.push_back(additive);

      operators.push_back(AST_Node_Type::Multiplicative);
      std::vector<std::string> multiplicative;
      multiplicative += "*", "/", "%";
      operator_matches.push_back(multiplicative);

      operators.push_back(AST_Node_Type::Dot_Access);
      std::vector<std::string> dot_access;
      dot_access += ".";
      operator_matches.push_back(dot_access);
    }
    /**
     * Prints the parsed ast_nodes as a tree
     */
    /*
    void debug_print(AST_NodePtr t, std::string prepend = "") {
      std::cout << prepend << "(" << ast_node_type_to_string(t->identifier) << ") " << t->text << " : " << t->start.line << ", " << t->start.column << std::endl;
      for (unsigned int j = 0; j < t->children.size(); ++j) {
        debug_print(t->children[j], prepend + "  ");
      }
    }
    */

    /**
     * Shows the current stack of matched ast_nodes
     */
    void show_match_stack() {
      for (unsigned int i = 0; i < match_stack.size(); ++i) {
        //debug_print(match_stack[i]);
        std::cout << match_stack[i]->to_string();
      }
    }

    /**
     * Clears the stack of matched ast_nodes
     */
    void clear_match_stack() {
      match_stack.clear();
    }

    /**
     * Returns the front-most AST node
     */
    AST_NodePtr ast() {
      return match_stack.front();
    }

    /**
     * Helper function that collects ast_nodes from a starting position to the top of the stack into a new AST node
     */
    void build_match(AST_NodePtr t, int match_start) {
      int pos_line_start, pos_col_start, pos_line_stop, pos_col_stop;
      int is_deep = false;
      
      //so we want to take everything to the right of this and make them children
      if (match_start != int(match_stack.size())) {
        pos_line_start = match_stack[match_start]->start.line;
        pos_col_start = match_stack[match_start]->start.column;
        pos_line_stop = line;
        pos_col_stop = col;
        is_deep = true;
      }
      else {
        pos_line_start = line;
        pos_col_start = col;
        pos_line_stop = line;
        pos_col_stop = col;
      }

      t->filename = filename;
      t->start.line = pos_line_start;
      t->start.column = pos_col_start;
      t->end.line = pos_line_stop;
      t->end.column = pos_col_stop;
      
      if (is_deep) {
        t->children.assign(match_stack.begin() + (match_start), match_stack.end());
        match_stack.erase(match_stack.begin() + (match_start), match_stack.end());
        match_stack.push_back(t);
      }
      else {
        //todo: fix the fact that a successful match that captured no ast_nodes doesn't have any real start position
        match_stack.push_back(t);
      }
    }

    /**
     * Does ranged char check
     */
    inline bool char_between(char start, char end) {
      if ((*input_pos >= start) && (*input_pos <= end)) {
        return true;
      }
      else {
        return false;
      }
    }

    /**
     * Check to see if there is more text parse
     */
    inline bool has_more_input() {
      return (input_pos != input_end);
    }
                                
    /**
     * Skips any multi-line or single-line comment
     */
    bool SkipComment() {
      bool retval = false;

      if (Symbol_(multiline_comment_begin.c_str())) {
        while (input_pos != input_end) {
          if (Symbol_(multiline_comment_end.c_str())) {
            break;
          }
          else if (!Eol_()) {
            ++col;
            ++input_pos;
          }
        }
        retval = true;
      }
      else if (Symbol_(singleline_comment.c_str())) {
        while (input_pos != input_end) {
          if (Symbol_("\r\n")) {
            input_pos -= 2;
            break;
          }
          else if (Char_('\n')) {
            --input_pos;
            break;
          }
          else {
            ++col;
            ++input_pos;
          }
        }
        retval = true;
      }
      return retval;
    }

    /**
     * Skips ChaiScript whitespace, which means space and tab, but not cr/lf
     */
    bool SkipWS() {
      bool retval = false;
      while (has_more_input()) {
        if ((*input_pos == ' ') || (*input_pos == '\t')) {
          ++input_pos;
          ++col;
          retval = true;
        }
        else if (SkipComment()) {
          retval = true;
        }
        else {
          break;
        }
      }
      return retval;
    }

    /**
     * Reads a floating point value from input, without skipping initial whitespace
     */
    bool Float_() {
      bool retval = false;
      std::string::const_iterator start = input_pos;

      if (has_more_input() && (char_between('0', '9') || (*input_pos == '.'))) {
        while (has_more_input() && char_between('0', '9')) {
          ++input_pos;
          ++col;
        }
        if (has_more_input() && (*input_pos == '.')) {
          ++input_pos;
          ++col;
          if (has_more_input() && char_between('0', '9')) {
            retval = true;
            while (has_more_input() && char_between('0', '9')) {
              ++input_pos;
              ++col;
            }
          }
          else {
            --input_pos;
            --col;
          }
        }
      }
      return retval;
    }

    /**
     * Reads a floating point value from input, without skipping initial whitespace
     */
    bool Hex_() {
      bool retval = false;
      if (has_more_input() && (*input_pos == '0')) {
        ++input_pos;
        ++col;

        if (has_more_input() && ((*input_pos == 'x') || (*input_pos == 'X'))) {
          ++input_pos;
          ++col;
          if (has_more_input() && (char_between('0', '9') ||
                                   char_between('a', 'f') ||
                                   char_between('A', 'F'))) {
            retval = true;
            while (has_more_input() && (char_between('0', '9') ||
                                        char_between('a', 'f') ||
                                        char_between('A', 'F'))) {
              ++input_pos;
              ++col;
            }
          }
          else {
            --input_pos;
            --col;
          }
        }
        else {
          --input_pos;
          --col;
        }
      }

      return retval;
    }

    /**
     * Reads a floating point value from input, without skipping initial whitespace
     */
    bool Binary_() {
      bool retval = false;
      if (has_more_input() && (*input_pos == '0')) {
        ++input_pos;
        ++col;

        if (has_more_input() && ((*input_pos == 'b') || (*input_pos == 'B'))) {
          ++input_pos;
          ++col;
          if (has_more_input() && char_between('0', '1')) {
            retval = true;
            while (has_more_input() && char_between('0', '1')) {
              ++input_pos;
              ++col;
            }
          }
          else {
            --input_pos;
            --col;
          }
        }
        else {
          --input_pos;
          --col;
        }
      }

      return retval;
    }

    /**
     * Reads a number from the input, detecting if it's an integer or floating point
     */
    bool Num(bool capture = false) {
      SkipWS();

      if (!capture) {
        return Hex_() || Float_();
      }
      else {
        std::string::const_iterator start = input_pos;
        int prev_col = col;
        int prev_line = line;
        if (has_more_input() && (char_between('0', '9') || (*input_pos == '.')) ) {
          if (Hex_()) {
            std::string match(start, input_pos);
            std::stringstream ss(match);
            unsigned int temp_int;
            ss >> std::hex >> temp_int;

            std::ostringstream out_int;
            out_int << int(temp_int);
            AST_NodePtr t(new Int_AST_Node(out_int.str(), AST_Node_Type::Int, filename, prev_line, prev_col, line, col));
            match_stack.push_back(t);
            return true;
          }
          if (Binary_()) {
            std::string match(start, input_pos);
            int temp_int = 0;
            unsigned int pos = 0, end = match.length();

            while ((pos < end) && (pos < (2 + sizeof(int) * 8))) {
              temp_int <<= 1;
              if (match[pos] == '1') {
                temp_int += 1;
              }
              ++pos;
            }

            std::ostringstream out_int;
            out_int << temp_int;
            AST_NodePtr t(new Int_AST_Node(out_int.str(), AST_Node_Type::Int, filename, prev_line, prev_col, line, col));
            match_stack.push_back(t);
            return true;
          }
          if (Float_()) {
            std::string match(start, input_pos);
            AST_NodePtr t(new Float_AST_Node(match, AST_Node_Type::Float, filename, prev_line, prev_col, line, col));
            match_stack.push_back(t);
            return true;
          }
          else {
            std::string match(start, input_pos);
            if ((match.size() > 0) && (match[0] == '0')) {
              std::stringstream ss(match);
              unsigned int temp_int;
              ss >> std::oct >> temp_int;

              std::ostringstream out_int;
              out_int << int(temp_int);
              AST_NodePtr t(new Int_AST_Node(out_int.str(), AST_Node_Type::Int, filename, prev_line, prev_col, line, col));
              match_stack.push_back(t);
            }
            else {
              AST_NodePtr t(new Int_AST_Node(match, AST_Node_Type::Int, filename, prev_line, prev_col, line, col));
              match_stack.push_back(t);
            }
            return true;
          }
        }
        else {
          return false;
        }
      }
    }

    /**
     * Reads an identifier from input which conforms to C's identifier naming conventions, without skipping initial whitespace
     */
    bool Id_() {
      bool retval = false;
      if (has_more_input() && (char_between('A', 'Z') || (*input_pos == '_') || char_between('a', 'z'))) {
        retval = true;
        while (has_more_input() && (char_between('A', 'Z') || (*input_pos == '_') ||
                                    char_between('a', 'z') || char_between('0', '9'))) {
          ++input_pos;
          ++col;
        }
      }
      else if (has_more_input() && (*input_pos == '`')) {
        retval = true;
        ++col;
        ++input_pos;
        std::string::const_iterator start = input_pos;
                
        while (has_more_input() && (*input_pos != '`')) {
          if (Eol()) {
            throw Eval_Error("Carriage return in identifier literal", File_Position(line, col), filename);
          }
          else {
            ++input_pos;
            ++col;
          }
        }

        if (start == input_pos) {
          throw Eval_Error("Missing contents of identifier literal", File_Position(line, col), filename);
        }
        else if (input_pos == input_end) {
          throw Eval_Error("Incomplete identifier literal", File_Position(line, col), filename);
        }

        ++col;
        ++input_pos;
      }
      return retval;
    }

    /**
     * Reads (and potentially captures) an identifier from input
     */
    bool Id(bool capture = false) {
      SkipWS();

      if (!capture) {
        return Id_();
      }
      else {
        std::string::const_iterator start = input_pos;
        int prev_col = col;
        int prev_line = line;
        if (Id_()) {
          if (*start == '`') {
            //Id Literal
            std::string match(start+1, input_pos-1);
            AST_NodePtr t(new Id_AST_Node(match, AST_Node_Type::Id, filename, prev_line, prev_col, line, col));
            match_stack.push_back(t);
            return true;
          }
          else {
            std::string match(start, input_pos);
            AST_NodePtr t(new Id_AST_Node(match, AST_Node_Type::Id, filename, prev_line, prev_col, line, col));
            match_stack.push_back(t);
            return true;
          }
        }
        else {
          return false;
        }
      }
    }

    /**
     * Checks for a node annotation of the form "#<annotation>"
     */
    bool Annotation() {
      SkipWS();
      std::string::const_iterator start = input_pos;
      int prev_col = col;
      int prev_line = line;
      if (Symbol_("#")) {
        do {
          while (input_pos != input_end) {
            if (Eol_()) {
              break;
            }
            else {
              ++col;
              ++input_pos;
            }
          }
        } while (Symbol("#"));

        std::string match(start, input_pos);
        AST_NodePtr t(new Annotation_AST_Node(match, AST_Node_Type::Annotation, filename, prev_line, prev_col, line, col));
        match_stack.push_back(t);
        return true;
      }
      else {
        return false;
      }
    }

    /**
     * Reads a quoted string from input, without skipping initial whitespace
     */
    bool Quoted_String_() {
      bool retval = false;
      char prev_char = 0;
      if (has_more_input() && (*input_pos == '\"')) {
        retval = true;
        prev_char = *input_pos;
        ++input_pos;
        ++col;

        while (has_more_input() && ((*input_pos != '\"') || ((*input_pos == '\"') && (prev_char == '\\')))) {
          if (!Eol_()) {
            if (prev_char == '\\') {
              prev_char = 0;
            }
            else {
              prev_char = *input_pos;
            }
            ++input_pos;
            ++col;
          }
        }

        if (has_more_input()) {
          ++input_pos;
          ++col;
        }
        else {
          throw Eval_Error("Unclosed quoted string", File_Position(line, col), filename);
        }
      }
      return retval;
    }

    /**
     * Reads (and potentially captures) a quoted string from input.  Translates escaped sequences.
     */
    bool Quoted_String(bool capture = false) {
      SkipWS();

      if (!capture) {
        return Quoted_String_();
      }
      else {
        std::string::const_iterator start = input_pos;
        int prev_col = col;
        int prev_line = line;
        if (Quoted_String_()) {
          std::string match;
          bool is_escaped = false;
          bool is_interpolated = false;
          bool saw_interpolation_marker = false;
          int prev_stack_top = match_stack.size();

          //for (std::string::iterator s = start + 1, end = input_pos - 1; s != end; ++s) {
          std::string::const_iterator s = start + 1, end = input_pos - 1;

          while (s != end) {
            if (saw_interpolation_marker) {
              if (*s == '{') {
                //We've found an interpolation point

                if (is_interpolated) {
                  //If we've seen previous interpolation, add on instead of making a new one
                  AST_NodePtr plus(new Str_AST_Node("+", AST_Node_Type::Str, filename, prev_line, prev_col, line, col));
                  match_stack.push_back(plus);

                  AST_NodePtr t(new Quoted_String_AST_Node(match, AST_Node_Type::Quoted_String, filename, prev_line, prev_col, line, col));
                  match_stack.push_back(t);

                  build_match(AST_NodePtr(new Additive_AST_Node()), prev_stack_top);
                }
                else {
                  AST_NodePtr t(new Quoted_String_AST_Node(match, AST_Node_Type::Quoted_String, filename, prev_line, prev_col, line, col));
                  match_stack.push_back(t);
                }

                //We've finished with the part of the string up to this point, so clear it
                match = "";

                AST_NodePtr plus(new Str_AST_Node("+", AST_Node_Type::Str, filename, prev_line, prev_col, line, col));
                match_stack.push_back(plus);

                std::string eval_match;

                ++s;
                while ((*s != '}') && (s != end)) {
                  eval_match.push_back(*s);
                  ++s;
                }
                if (*s == '}') {
                  is_interpolated = true;
                  ++s;

                  int tostr_stack_top = match_stack.size();

                  AST_NodePtr tostr(new Id_AST_Node("to_string", AST_Node_Type::Id, filename, prev_line, prev_col, line, col));
                  match_stack.push_back(tostr);

                  int ev_stack_top = match_stack.size();

                  AST_NodePtr ev(new Id_AST_Node("eval", AST_Node_Type::Id, filename, prev_line, prev_col, line, col));
                  match_stack.push_back(ev);

                  int arg_stack_top = match_stack.size();

                  AST_NodePtr t(new Quoted_String_AST_Node(eval_match, AST_Node_Type::Quoted_String, filename, prev_line, prev_col, line, col));
                  match_stack.push_back(t);

                  build_match(AST_NodePtr(new Arg_List_AST_Node()), arg_stack_top);

                  build_match(AST_NodePtr(new Inplace_Fun_Call_AST_Node()), ev_stack_top);

                  build_match(AST_NodePtr(new Arg_List_AST_Node()), ev_stack_top);

                  build_match(AST_NodePtr(new Fun_Call_AST_Node()), tostr_stack_top);

                  build_match(AST_NodePtr(new Additive_AST_Node()), prev_stack_top);
                }
                else {
                  throw Eval_Error("Unclosed in-string eval", File_Position(prev_line, prev_col), filename);
                }
              }
              else {
                match.push_back('$');
              }
              saw_interpolation_marker = false;
            }
            else {
              if (*s == '\\') {
                if (is_escaped) {
                  match.push_back('\\');
                  is_escaped = false;
                }
                else {
                  is_escaped = true;
                }
              }
              else {
                if (is_escaped) {
                  switch (*s) {
                  case ('b') : match.push_back('\b'); break;
                  case ('f') : match.push_back('\f'); break;
                  case ('n') : match.push_back('\n'); break;
                  case ('r') : match.push_back('\r'); break;
                  case ('t') : match.push_back('\t'); break;
                  case ('\'') : match.push_back('\''); break;
                  case ('\"') : match.push_back('\"'); break;
                  case ('$') : match.push_back('$'); break;
                  default: throw Eval_Error("Unknown escaped sequence in string", File_Position(prev_line, prev_col), filename);
                  }
                }
                else if (*s == '$') {
                  saw_interpolation_marker = true;
                }
                else {
                  match.push_back(*s);
                }
                is_escaped = false;
              }
              ++s;
            }
          }
          if (is_interpolated) {
            AST_NodePtr plus(new Str_AST_Node("+", AST_Node_Type::Str, filename, prev_line, prev_col, line, col));
            match_stack.push_back(plus);

            AST_NodePtr t(new Quoted_String_AST_Node(match, AST_Node_Type::Quoted_String, filename, prev_line, prev_col, line, col));
            match_stack.push_back(t);

            build_match(AST_NodePtr(new Additive_AST_Node()), prev_stack_top);
          }
          else {
            AST_NodePtr t(new Quoted_String_AST_Node(match, AST_Node_Type::Quoted_String, filename, prev_line, prev_col, line, col));
            match_stack.push_back(t);
          }
          return true;
        }
        else {
          return false;
        }
      }
    }

    /**
     * Reads a character group from input, without skipping initial whitespace
     */
    bool Single_Quoted_String_() {
      bool retval = false;
      char prev_char = 0;
      if (has_more_input() && (*input_pos == '\'')) {
        retval = true;
        prev_char = *input_pos;
        ++input_pos;
        ++col;

        while (has_more_input() && ((*input_pos != '\'') || ((*input_pos == '\'') && (prev_char == '\\')))) {
          if (!Eol_()) {
            if (prev_char == '\\') {
              prev_char = 0;
            }
            else {
              prev_char = *input_pos;
            }
            ++input_pos;
            ++col;
          }
        }

        if (input_pos != input_end) {
          ++input_pos;
          ++col;
        }
        else {
          throw Eval_Error("Unclosed single-quoted string", File_Position(line, col), filename);
        }
      }
      return retval;
    }

    /**
     * Reads (and potentially captures) a char group from input.  Translates escaped sequences.
     */
    bool Single_Quoted_String(bool capture = false) {
      SkipWS();

      if (!capture) {
        return Single_Quoted_String_();
      }
      else {
        std::string::const_iterator start = input_pos;
        int prev_col = col;
        int prev_line = line;
        if (Single_Quoted_String_()) {
          std::string match;
          bool is_escaped = false;
          for (std::string::const_iterator s = start + 1, end = input_pos - 1; s != end; ++s) {
            if (*s == '\\') {
              if (is_escaped) {
                match.push_back('\\');
                is_escaped = false;
              }
              else {
                is_escaped = true;
              }
            }
            else {
              if (is_escaped) {
                switch (*s) {
                case ('b') : match.push_back('\b'); break;
                case ('f') : match.push_back('\f'); break;
                case ('n') : match.push_back('\n'); break;
                case ('r') : match.push_back('\r'); break;
                case ('t') : match.push_back('\t'); break;
                case ('\'') : match.push_back('\''); break;
                case ('\"') : match.push_back('\"'); break;
                default: throw Eval_Error("Unknown escaped sequence in string", File_Position(prev_line, prev_col), filename);
                }
              }
              else {
                match.push_back(*s);
              }
              is_escaped = false;
            }
          }
          AST_NodePtr t(new Single_Quoted_String_AST_Node(match, AST_Node_Type::Single_Quoted_String, filename, prev_line, prev_col, line, col));
          match_stack.push_back(t);
          return true;
        }
        else {
          return false;
        }
      }
    }

    /**
     * Reads a char from input if it matches the parameter, without skipping initial whitespace
     */
    bool Char_(char c) {
      bool retval = false;
      if (has_more_input() && (*input_pos == c)) {
        ++input_pos;
        ++col;
        retval = true;
      }

      return retval;
    }

    /**
     * Reads (and potentially captures) a char from input if it matches the parameter
     */
    bool Char(char c, bool capture = false) {
      SkipWS();

      if (!capture) {
        return Char_(c);
      }
      else {
        std::string::const_iterator start = input_pos;
        int prev_col = col;
        int prev_line = line;
        if (Char_(c)) {
          std::string match(start, input_pos);
          AST_NodePtr t(new Char_AST_Node(match, AST_Node_Type::Char, filename, prev_line, prev_col, line, col));
          match_stack.push_back(t);
          return true;
        }
        else {
          return false;
        }
      }
    }

    /**
     * Reads a string from input if it matches the parameter, without skipping initial whitespace
     */
    bool Keyword_(const char *s) {
      bool retval = false;
      int len = strlen(s);

      if ((input_end - input_pos) >= len) {
        std::string::const_iterator tmp = input_pos;
        for (int i = 0; i < len; ++i) {
          if (*tmp != s[i]) {
            return false;
          }
          ++tmp;
        }
        retval = true;
        input_pos = tmp;
        col += len;
      }

      return retval;
    }

    /**
     * Reads (and potentially captures) a string from input if it matches the parameter
     */
    bool Keyword(const char *s, bool capture = false) {
      SkipWS();

      if (!capture) {
        std::string::const_iterator start = input_pos;
        int prev_col = col;
        int prev_line = line;
        bool retval = Keyword_(s);
        if (retval) {
          //todo: fix this.  Hacky workaround for preventing substring matches
          if (has_more_input() && (char_between('A', 'Z') || (*input_pos == '_') ||
                                   char_between('a', 'z') || char_between('0', '9'))) {
            input_pos = start;
            col = prev_col;
            line = prev_line;
            return false;
          }
          return true;
        }
        else {
          return retval;
        }
      }
      else {
        std::string::const_iterator start = input_pos;
        int prev_col = col;
        int prev_line = line;
        if (Keyword_(s)) {
          //todo: fix this.  Hacky workaround for preventing substring matches
          if (has_more_input() && (char_between('A', 'Z') || (*input_pos == '_') ||
                                   char_between('a', 'z') || char_between('0', '9'))) {
            input_pos = start;
            col = prev_col;
            line = prev_line;
            return false;
          }
          std::string match(start, input_pos);
          AST_NodePtr t(new Str_AST_Node(match, AST_Node_Type::Str, filename, prev_line, prev_col, line, col));
          match_stack.push_back(t);
          return true;
        }
        else {
          return false;
        }
      }
    }

    /**
     * Reads a symbol group from input if it matches the parameter, without skipping initial whitespace
     */
    bool Symbol_(const char *s) {
      bool retval = false;
      int len = strlen(s);

      if ((input_end - input_pos) >= len) {
        std::string::const_iterator tmp = input_pos;
        for (int i = 0; i < len; ++i) {
          if (*tmp != s[i]) {
            return false;
          }
          ++tmp;
        }
        retval = true;
        input_pos = tmp;
        col += len;
      }

      return retval;
    }

    /**
     * Reads (and potentially captures) a symbol group from input if it matches the parameter
     */
    bool Symbol(const char *s, bool capture = false, bool disallow_prevention=false) {
      SkipWS();

      if (!capture) {
        std::string::const_iterator start = input_pos;
        int prev_col = col;
        int prev_line = line;
        bool retval = Symbol_(s);
        if (retval) {
          //todo: fix this.  Hacky workaround for preventing substring matches
          if (has_more_input() && (disallow_prevention == false) &&
              ((*input_pos == '+') || (*input_pos == '-') || (*input_pos == '*') || (*input_pos == '/') ||
               (*input_pos == '|') || (*input_pos == '&') || (*input_pos == '^') || (*input_pos == '=') ||
               (*input_pos == '.') || (*input_pos == '<') || (*input_pos == '>'))) {
            input_pos = start;
            col = prev_col;
            line = prev_line;
            return false;
          }
          return true;
        }
        else {
          return retval;
        }
      }
      else {
        std::string::const_iterator start = input_pos;
        int prev_col = col;
        int prev_line = line;
        if (Symbol_(s)) {
          //todo: fix this.  Hacky workaround for preventing substring matches
          if (has_more_input() && (disallow_prevention == false) &&
              ((*input_pos == '+') || (*input_pos == '-') || (*input_pos == '*') || (*input_pos == '/') ||
               (*input_pos == '|') || (*input_pos == '&') || (*input_pos == '^') || (*input_pos == '=') ||
               (*input_pos == '.') || (*input_pos == '<') || (*input_pos == '>'))) {
            input_pos = start;
            col = prev_col;
            line = prev_line;
            return false;
          }
          else {
            std::string match(start, input_pos);
            AST_NodePtr t(new Str_AST_Node(match, AST_Node_Type::Str, filename, prev_line, prev_col, line, col));
            match_stack.push_back(t);
            return true;
          }
        }
        else {
          return false;
        }
      }
    }

    /**
     * Reads an end-of-line group from input, without skipping initial whitespace
     */
    bool Eol_() {
      bool retval = false;

      if (has_more_input() && (Symbol_("\r\n") || Char_('\n'))) {
        retval = true;
        ++line;
        col = 1;
      }
      else if (has_more_input() && Char_(';')) {
        retval = true;
      }

      return retval;
    }

    /**
     * Reads (and potentially captures) an end-of-line group from input
     */
    bool Eol(bool capture = false) {
      SkipWS();

      if (!capture) {
        return Eol_();
      }
      else {
        std::string::const_iterator start = input_pos;
        int prev_col = col;
        int prev_line = line;
        if (Eol_()) {
          std::string match(start, input_pos);
          AST_NodePtr t(new Eol_AST_Node(match, AST_Node_Type::Eol, filename, prev_line, prev_col, line, col));
          match_stack.push_back(t);
          return true;
        }
        else {
          return false;
        }
      }
    }

    /**
     * Reads a comma-separated list of values from input
     */
    bool Arg_List() {
      bool retval = false;

      int prev_stack_top = match_stack.size();

      if (Equation()) {
        retval = true;
        while (Eol()) {}
        if (Char(',')) {
          do {
            while (Eol()) {}
            if (!Equation()) {
              throw Eval_Error("Unexpected value in parameter list", File_Position(line, col), filename);
            }
          } while (retval && Char(','));
        }
        build_match(AST_NodePtr(new Arg_List_AST_Node()), prev_stack_top);
      }

      return retval;
    }

    /**
     * Reads possible special container values, including ranges and map_pairs
     */
    bool Container_Arg_List() {
      bool retval = false;

      int prev_stack_top = match_stack.size();

      if (Value_Range()) {
        retval = true;
        build_match(AST_NodePtr(new Arg_List_AST_Node()), prev_stack_top);
      }
      else if (Map_Pair()) {
        retval = true;
        while (Eol()) {}
        if (Char(',')) {
          do {
            while (Eol()) {}
            if (!Map_Pair()) {
              throw Eval_Error("Unexpected value in container", File_Position(line, col), filename);
            }
          } while (retval && Char(','));
        }
        build_match(AST_NodePtr(new Arg_List_AST_Node()), prev_stack_top);
      }

      return retval;

    }

    /**
     * Reads a lambda (anonymous function) from input
     */
    bool Lambda() {
      bool retval = false;

      int prev_stack_top = match_stack.size();

      if (Keyword("fun")) {
        retval = true;

        if (Char('(')) {
          Arg_List();
          if (!Char(')')) {
            throw Eval_Error("Incomplete anonymous function", File_Position(line, col), filename);
          }
        }

        while (Eol()) {}

        if (!Block()) {
          throw Eval_Error("Incomplete anonymous function", File_Position(line, col), filename);
        }

        build_match(AST_NodePtr(new Lambda_AST_Node()), prev_stack_top);
      }

      return retval;
    }

    /**
     * Reads a function definition from input
     */
    bool Def() {
      bool retval = false;
      bool is_annotated = false;
      bool is_method = false;
      AST_NodePtr annotation;

      if (Annotation()) {
        while (Eol_()) {}
        annotation = match_stack.back();
        match_stack.pop_back();
        is_annotated = true;
      }

      int prev_stack_top = match_stack.size();

      if (Keyword("def")) {
        retval = true;

        if (!Id(true)) {
          throw Eval_Error("Missing function name in definition", File_Position(line, col), filename);
        }

        if (Symbol("::", false)) {
          //We're now a method
          is_method = true;

          if (!Id(true)) {
            throw Eval_Error("Missing method name in definition", File_Position(line, col), filename);
          }
        }

        if (Char('(')) {
          Arg_List();
          if (!Char(')')) {
            throw Eval_Error("Incomplete function definition", File_Position(line, col), filename);
          }
        }

        while (Eol()) {}

        if (Char(':')) {
          if (!Operator()) {
            throw Eval_Error("Missing guard expression for function", File_Position(line, col), filename);
          }
        }

        while (Eol()) {}
        if (!Block()) {
          throw Eval_Error("Incomplete function definition", File_Position(line, col), filename);
        }

        if (is_method) {
          build_match(AST_NodePtr(new Method_AST_Node()), prev_stack_top);
        }
        else {
          build_match(AST_NodePtr(new Def_AST_Node()), prev_stack_top);
        }

        if (is_annotated) {
          match_stack.back()->annotation = annotation;
        }
      }

      return retval;
    }

    /**
     * Reads a function definition from input
     */
    bool Try() {
      bool retval = false;

      int prev_stack_top = match_stack.size();

      if (Keyword("try")) {
        retval = true;

        while (Eol()) {}

        if (!Block()) {
          throw Eval_Error("Incomplete 'try' block", File_Position(line, col), filename);
        }

        bool has_matches = true;
        while (has_matches) {
          while (Eol()) {}
          has_matches = false;
          if (Keyword("catch", false)) {
            int catch_stack_top = match_stack.size();
            if (Char('(')) {
              if (!(Id(true) && Char(')'))) {
                throw Eval_Error("Incomplete 'catch' expression", File_Position(line, col), filename);
              }
              if (Char(':')) {
                if (!Operator()) {
                  throw Eval_Error("Missing guard expression for catch", File_Position(line, col), filename);
                }
              }
            }

            while (Eol()) {}

            if (!Block()) {
              throw Eval_Error("Incomplete 'catch' block", File_Position(line, col), filename);
            }
            build_match(AST_NodePtr(new Catch_AST_Node()), catch_stack_top);
            has_matches = true;
          }
        }
        while (Eol()) {}
        if (Keyword("finally", false)) {
          int finally_stack_top = match_stack.size();

          while (Eol()) {}

          if (!Block()) {
            throw Eval_Error("Incomplete 'finally' block", File_Position(line, col), filename);
          }
          build_match(AST_NodePtr(new Finally_AST_Node()), finally_stack_top);
        }

        build_match(AST_NodePtr(new Try_AST_Node()), prev_stack_top);
      }

      return retval;
    }

    /**
     * Reads an if/elseif/else block from input
     */
    bool If() {
      bool retval = false;

      int prev_stack_top = match_stack.size();

      if (Keyword("if")) {
        retval = true;

        if (!Char('(')) {
          throw Eval_Error("Incomplete 'if' expression", File_Position(line, col), filename);
        }

        if (!(Operator() && Char(')'))) {
          throw Eval_Error("Incomplete 'if' expression", File_Position(line, col), filename);
        }

        while (Eol()) {}

        if (!Block()) {
          throw Eval_Error("Incomplete 'if' block", File_Position(line, col), filename);
        }

        bool has_matches = true;
        while (has_matches) {
          while (Eol()) {}
          has_matches = false;
          if (Keyword("else", true)) {
            if (Keyword("if")) {
              match_stack.back()->text = "else if";
              if (!Char('(')) {
                throw Eval_Error("Incomplete 'else if' expression", File_Position(line, col), filename);
              }

              if (!(Operator() && Char(')'))) {
                throw Eval_Error("Incomplete 'else if' expression", File_Position(line, col), filename);
              }

              while (Eol()) {}

              if (!Block()) {
                throw Eval_Error("Incomplete 'else if' block", File_Position(line, col), filename);
              }
              has_matches = true;
            }
            else {
              while (Eol()) {}

              if (!Block()) {
                throw Eval_Error("Incomplete 'else' block", File_Position(line, col), filename);
              }
              has_matches = true;
            }
          }
        }

        build_match(AST_NodePtr(new If_AST_Node()), prev_stack_top);
      }

      return retval;
    }

    /**
     * Reads a while block from input
     */
    bool While() {
      bool retval = false;

      int prev_stack_top = match_stack.size();

      if (Keyword("while")) {
        retval = true;

        if (!Char('(')) {
          throw Eval_Error("Incomplete 'while' expression", File_Position(line, col), filename);
        }

        if (!(Operator() && Char(')'))) {
          throw Eval_Error("Incomplete 'while' expression", File_Position(line, col), filename);
        }

        while (Eol()) {}

        if (!Block()) {
          throw Eval_Error("Incomplete 'while' block", File_Position(line, col), filename);
        }

        build_match(AST_NodePtr(new While_AST_Node()), prev_stack_top);
      }

      return retval;
    }

    /**
     * Reads the C-style for conditions from input
     */
    bool For_Guards() {
      Equation();

      if (Char(';') && Operator() && Char(';') && Equation()) {
        return true;
      }
      else {
        throw Eval_Error("Incomplete conditions in 'for' loop", File_Position(line, col), filename);
      }
    }

    /**
     * Reads a for block from input
     */
    bool For() {
      bool retval = false;

      int prev_stack_top = match_stack.size();

      if (Keyword("for")) {
        retval = true;

        if (!Char('(')) {
          throw Eval_Error("Incomplete 'for' expression", File_Position(line, col), filename);
        }

        if (!(For_Guards() && Char(')'))) {
          throw Eval_Error("Incomplete 'for' expression", File_Position(line, col), filename);
        }

        while (Eol()) {}

        if (!Block()) {
          throw Eval_Error("Incomplete 'for' block", File_Position(line, col), filename);
        }

        build_match(AST_NodePtr(new For_AST_Node()), prev_stack_top);
      }

      return retval;
    }

    /**
     * Reads a curly-brace C-style block from input
     */
    bool Block() {
      bool retval = false;

      int prev_stack_top = match_stack.size();

      if (Char('{')) {
        retval = true;

        Statements();
        if (!Char('}')) {
          throw Eval_Error("Incomplete block", File_Position(line, col), filename);
        }

        build_match(AST_NodePtr(new Block_AST_Node()), prev_stack_top);
      }

      return retval;
    }

    /**
     * Reads a return statement from input
     */
    bool Return() {
      bool retval = false;

      int prev_stack_top = match_stack.size();

      if (Keyword("return")) {
        retval = true;

        Operator();
        build_match(AST_NodePtr(new Return_AST_Node()), prev_stack_top);
      }

      return retval;
    }

    /**
     * Reads a break statement from input
     */
    bool Break() {
      bool retval = false;

      int prev_stack_top = match_stack.size();

      if (Keyword("break")) {
        retval = true;

        build_match(AST_NodePtr(new Break_AST_Node()), prev_stack_top);
      }

      return retval;
    }

    /**
     * Reads an identifier, then proceeds to check if it's a function or array call
     */
    bool Id_Fun_Array() {
      bool retval = false;
      std::string::const_iterator prev_pos = input_pos;

      unsigned int prev_stack_top = match_stack.size();
      if (Id(true)) {
        retval = true;
        bool has_more = true;

        while (has_more) {
          has_more = false;

          if (Char('(')) {
            has_more = true;

            Arg_List();
            if (!Char(')')) {
              throw Eval_Error("Incomplete function call", File_Position(line, col), filename);
            }

            build_match(AST_NodePtr(new Fun_Call_AST_Node()), prev_stack_top);
          }
          else if (Char('[')) {
            has_more = true;

            if (!(Operator() && Char(']'))) {
              throw Eval_Error("Incomplete array access", File_Position(line, col), filename);
            }

            build_match(AST_NodePtr(new Array_Call_AST_Node()), prev_stack_top);
          }
        }
      }

      return retval;
    }

    /**
     * Reads a variable declaration from input
     */
    bool Var_Decl() {
      bool retval = false;

      int prev_stack_top = match_stack.size();

      if (Keyword("var")) {
        retval = true;

        if (!Id(true)) {
          throw Eval_Error("Incomplete variable declaration", File_Position(line, col), filename);
        }

        build_match(AST_NodePtr(new Var_Decl_AST_Node()), prev_stack_top);
      }
      else if (Keyword("attr")) {
        retval = true;

        if (!Id(true)) {
          throw Eval_Error("Incomplete attribute declaration", File_Position(line, col), filename);
        }
        if (!Symbol("::", false)) {
          throw Eval_Error("Incomplete attribute declaration", File_Position(line, col), filename);
        }
        if (!Id(true)) {
          throw Eval_Error("Missing attribute name in definition", File_Position(line, col), filename);
        }


        build_match(AST_NodePtr(new Attr_Decl_AST_Node()), prev_stack_top);
      }

      return retval;
    }

    /**
     * Reads an expression surrounded by parentheses from input
     */
    bool Paren_Expression() {
      bool retval = false;

      if (Char('(')) {
        retval = true;
        if (!Operator()) {
          throw Eval_Error("Incomplete expression", File_Position(line, col), filename);
        }
        if (!Char(')')) {
          throw Eval_Error("Missing closing parenthesis", File_Position(line, col), filename);
        }
      }
      return retval;
    }

    /**
     * Reads, and identifies, a short-form container initialization from input
     */
    bool Inline_Container() {
      bool retval = false;

      unsigned int prev_stack_top = match_stack.size();

      if (Char('[')) {
        retval = true;
        Container_Arg_List();
        if (!Char(']')) {
          throw Eval_Error("Missing closing square bracket", File_Position(line, col), filename);
        }
        if ((prev_stack_top != match_stack.size()) && (match_stack.back()->children.size() > 0)) {
          if (match_stack.back()->children[0]->identifier == AST_Node_Type::Value_Range) {
            build_match(AST_NodePtr(new Inline_Range_AST_Node()), prev_stack_top);
          }
          else if (match_stack.back()->children[0]->identifier == AST_Node_Type::Map_Pair) {
            build_match(AST_NodePtr(new Inline_Map_AST_Node()), prev_stack_top);
          }
          else {
            build_match(AST_NodePtr(new Inline_Array_AST_Node()), prev_stack_top);
          }
        }
        else {
          build_match(AST_NodePtr(new Inline_Array_AST_Node()), prev_stack_top);
        }
      }

      return retval;
    }

    /**
     * Reads a unary prefixed expression from input
     */
    bool Prefix() {
      bool retval = false;

      int prev_stack_top = match_stack.size();

      if (Symbol("++", true)) {
        retval = true;

        if (!Operator(operators.size()-1)) {
          throw Eval_Error("Incomplete '++' expression", File_Position(line, col), filename);
        }

        build_match(AST_NodePtr(new Prefix_AST_Node()), prev_stack_top);
      }
      else if (Symbol("--", true)) {
        retval = true;

        if (!Operator(operators.size()-1)) {
          throw Eval_Error("Incomplete '--' expression", File_Position(line, col), filename);
        }

        build_match(AST_NodePtr(new Prefix_AST_Node()), prev_stack_top);
      }
      else if (Char('-', true)) {
        retval = true;

        if (!Operator(operators.size()-1)) {
          throw Eval_Error("Incomplete unary '-' expression", File_Position(line, col), filename);
        }

        build_match(AST_NodePtr(new Prefix_AST_Node()), prev_stack_top);
      }
      else if (Char('+', true)) {
        retval = true;

        if (!Operator(operators.size()-1)) {
          throw Eval_Error("Incomplete unary '+' expression", File_Position(line, col), filename);
        }

        build_match(AST_NodePtr(new Prefix_AST_Node()), prev_stack_top);
      }
      else if (Char('!', true)) {
        retval = true;

        if (!Operator(operators.size()-1)) {
          throw Eval_Error("Incomplete '!' expression", File_Position(line, col), filename);
        }

        build_match(AST_NodePtr(new Prefix_AST_Node()), prev_stack_top);
      }
      else if (Char('~', true)) {
        retval = true;

        if (!Operator(operators.size()-1)) {
          throw Eval_Error("Incomplete '~' expression", File_Position(line, col), filename);
        }

        build_match(AST_NodePtr(new Prefix_AST_Node()), prev_stack_top);
      }

      return retval;
    }

    /**
     * Parses any of a group of 'value' style ast_node groups from input
     */
    bool Value() {
      if (Var_Decl() || Lambda() || Id_Fun_Array() || Num(true) || Prefix() || Quoted_String(true) || Single_Quoted_String(true) ||
          Paren_Expression() || Inline_Container()) {
        return true;
      }
      else {
        return false;
      }
    }
        
    bool Operator_Helper(int precedence) {
      for (unsigned int i = 0; i < operator_matches[precedence].size(); ++i) {
        if (Symbol(operator_matches[precedence][i].c_str(), true)) {
          return true;
        }
      }
      return false;
    }

    bool Operator(unsigned int precedence = 0) {
      bool retval = false;

      int prev_stack_top = match_stack.size();

      if (precedence < operators.size()) {
        if (Operator(precedence+1)) {
          retval = true;
          if (Operator_Helper(precedence)) {
            do {
              if (!Operator(precedence+1)) {
                throw Eval_Error("Incomplete " + std::string(ast_node_type_to_string(operators[precedence])) + " expression",
                                 File_Position(line, col), filename);
              }
            } while (Operator_Helper(precedence));

            switch (operators[precedence]) {
            case(AST_Node_Type::Comparison) :
              build_match(AST_NodePtr(new Comparison_AST_Node()), prev_stack_top);
              break;
            case(AST_Node_Type::Dot_Access) :
              build_match(AST_NodePtr(new Dot_Access_AST_Node()), prev_stack_top);
              break;
            case(AST_Node_Type::Additive) :
              build_match(AST_NodePtr(new Additive_AST_Node()), prev_stack_top);
              break;
            case(AST_Node_Type::Multiplicative) :
              build_match(AST_NodePtr(new Multiplicative_AST_Node()), prev_stack_top);
              break;
            case(AST_Node_Type::Shift) :
              build_match(AST_NodePtr(new Shift_AST_Node()), prev_stack_top);
              break;
            case(AST_Node_Type::Equality) :
              build_match(AST_NodePtr(new Equality_AST_Node()), prev_stack_top);
              break;
            case(AST_Node_Type::Bitwise_And) :
              build_match(AST_NodePtr(new Bitwise_And_AST_Node()), prev_stack_top);
              break;
            case(AST_Node_Type::Bitwise_Xor) :
              build_match(AST_NodePtr(new Bitwise_Xor_AST_Node()), prev_stack_top);
              break;
            case(AST_Node_Type::Bitwise_Or) :
              build_match(AST_NodePtr(new Bitwise_Or_AST_Node()), prev_stack_top);
              break;
            case(AST_Node_Type::Logical_And) :
              build_match(AST_NodePtr(new Logical_And_AST_Node()), prev_stack_top);
              break;
            case(AST_Node_Type::Logical_Or) :
              build_match(AST_NodePtr(new Logical_Or_AST_Node()), prev_stack_top);
              break;
            default:
              throw Eval_Error("Internal error: unhandled ast_node", File_Position(line, col), filename); 
            }
          }
        }
      }
      else {
        return Value();
      }

      return retval;
    }

    /**
     * Reads a pair of values used to create a map initialization from input
     */
    bool Map_Pair() {
      bool retval = false;

      int prev_stack_top = match_stack.size();

      if (Operator()) {
        retval = true;
        if (Symbol(":")) {
          do {
            if (!Operator()) {
              throw Eval_Error("Incomplete map pair", File_Position(line, col), filename);
            }
          } while (retval && Symbol(":"));

          build_match(AST_NodePtr(new Map_Pair_AST_Node()), prev_stack_top);
        }
      }

      return retval;
    }

    /**
     * Reads a pair of values used to create a range initialization from input
     */
    bool Value_Range() {
      bool retval = false;

      unsigned int prev_stack_top = match_stack.size();
      std::string::const_iterator prev_pos = input_pos;
      int prev_col = col;

      if (Operator()) {
        if (Symbol("..")) {
          retval = true;
          if (!Operator()) {
            throw Eval_Error("Incomplete value range", File_Position(line, col), filename);
          }

          build_match(AST_NodePtr(new Value_Range_AST_Node()), prev_stack_top);
        }
        else {
          input_pos = prev_pos;
          col = prev_col;
          while (prev_stack_top != match_stack.size()) {
            match_stack.pop_back();
          }
        }
      }

      return retval;
    }

    /**
     * Parses a string of binary equation operators
     */
    bool Equation() {
      bool retval = false;

      int prev_stack_top = match_stack.size();

      if (Operator()) {
        retval = true;
        if (Symbol("=", true, true) || Symbol(":=", true, true) || Symbol("+=", true, true) ||
            Symbol("-=", true, true) || Symbol("*=", true, true) || Symbol("/=", true, true) ||
            Symbol("%=", true, true) || Symbol("<<=", true, true) || Symbol(">>=", true, true) ||
            Symbol("&=", true, true) || Symbol("^=", true, true) || Symbol("|=", true, true)) {
          if (!Equation()) {
            throw Eval_Error("Incomplete equation", File_Position(line, col), filename);
          }

          build_match(AST_NodePtr(new Equation_AST_Node()), prev_stack_top);
        }
      }

      return retval;
    }

    /**
     * Top level parser, starts parsing of all known parses
     */
    bool Statements() {
      bool retval = false;

      bool has_more = true;
      bool saw_eol = true;

      while (has_more) {
        has_more = false;
        int prev_line = line;
        int prev_col = col;
        if (Def()) {
          if (!saw_eol) {
            throw Eval_Error("Two function definitions missing line separator", File_Position(prev_line, prev_col), filename);
          }
          has_more = true;
          retval = true;
          saw_eol = true;
        }
        else if (Try()) {
          if (!saw_eol) {
            throw Eval_Error("Two function definitions missing line separator", File_Position(prev_line, prev_col), filename);
          }
          has_more = true;
          retval = true;
          saw_eol = true;
        }
        else if (If()) {
          if (!saw_eol) {
            throw Eval_Error("Two function definitions missing line separator", File_Position(prev_line, prev_col), filename);
          }
          has_more = true;
          retval = true;
          saw_eol = true;
        }
        else if (While()) {
          if (!saw_eol) {
            throw Eval_Error("Two function definitions missing line separator", File_Position(prev_line, prev_col), filename);
          }
          has_more = true;
          retval = true;
          saw_eol = true;
        }
        else if (For()) {
          if (!saw_eol) {
            throw Eval_Error("Two function definitions missing line separator", File_Position(prev_line, prev_col), filename);
          }
          has_more = true;
          retval = true;
          saw_eol = true;
        }
        else if (Return()) {
          if (!saw_eol) {
            throw Eval_Error("Two expressions missing line separator", File_Position(prev_line, prev_col), filename);
          }
          has_more = true;
          retval = true;
          saw_eol = false;
        }
        else if (Break()) {
          if (!saw_eol) {
            throw Eval_Error("Two expressions missing line separator", File_Position(prev_line, prev_col), filename);
          }
          has_more = true;
          retval = true;
          saw_eol = false;
        }
        else if (Equation()) {
          if (!saw_eol) {
            throw Eval_Error("Two expressions missing line separator", File_Position(prev_line, prev_col), filename);
          }
          has_more = true;
          retval = true;
          saw_eol = false;
        }
        else if (Eol()) {
          has_more = true;
          retval = true;
          saw_eol = true;
        }
        else if (Block()) {
          has_more = true;
          retval = true;
          saw_eol = true;
        }
        else {
          has_more = false;
        }
      }

      return retval;
    }

    /**
     * Parses the given input string, tagging parsed ast_nodes with the given filename.
     */
    bool parse(const std::string &input, const char *fname) {
      input_pos = input.begin();
      input_end = input.end();
      line = 1; col = 1;
      filename = fname;

      if ((input.size() > 1) && (input[0] == '#') && (input[1] == '!')) {
        while ((input_pos != input_end) && (!Eol())) {
          ++input_pos;
        }
      }

      if (Statements()) {
        if (input_pos != input_end) {
          throw Eval_Error("Unparsed input", File_Position(line, col), fname);
        }
        else {
          build_match(AST_NodePtr(new File_AST_Node()), 0);
          return true;
        }
      }
      else {
        return false;
      }
    }

  };
}

#endif /* CHAISCRIPT_PARSER_HPP_ */