ginac/parser/parser.cpp

   1 #include <stdexcept>
   2 #include <sstream>
   3 #include "parser.hpp"
   4 #include "lexer.hpp"
   5 #include "debug.hpp"
   6 #include "mul.h"
   7 #include "constant.h"
   8
   9 namespace GiNaC
  10 {
  11
  12 /// identifier_expr:  identifier |  identifier '(' expression* ')'
  13 ex parser::parse_identifier_expr()
  14 {
  15         std::string name = scanner->str;
  16         get_next_tok();  // eat identifier.
  17
  18         if (token != '(') // symbol
  19                 return find_or_insert_symbol(name, syms, strict);
  20
  21         // function/ctor call.
  22         get_next_tok();  // eat (
  23         exvector args;
  24         if (token != ')') {
  25                 while (true) {
  26                         ex e = parse_expression();
  27                         args.push_back(e);
  28
  29                         if (token == ')')
  30                                 break;
  31
  32                         if (token != ',')
  33                                 throw std::invalid_argument("Expected ')' or ',' in argument list");
  34
  35                         get_next_tok();
  36                 }
  37         }
  38         // Eat the ')'.
  39         get_next_tok();
  40         prototype the_prototype = make_pair(name, args.size());
  41         prototype_table::const_iterator reader = funcs.find(the_prototype);
  42         if (reader == funcs.end()) {
  43                 bail_out(std::invalid_argument,
  44                         "no function \"" << name << "\" with " << args.size()
  45                         << " arguments");
  46         }
  47         ex ret = reader->second(args);
  48         return ret;
  49 }
  50
  51 /// paren_expr:  '(' expression ')'
  52 ex parser::parse_paren_expr()
  53 {
  54         get_next_tok();  // eat (.
  55         ex e = parse_expression();
  56
  57         if (token != ')')
  58                 throw std::invalid_argument("parser::parse_paren_expr: expected ')'");
  59         get_next_tok();  // eat ).
  60         return e;
  61 }
  62
  63 extern numeric* _num_1_p;
  64
  65 /// unary_expr: [+-] expression
  66 ex parser::parse_unary_expr(const int s)
  67 {
  68         // consume '-' (or '+')
  69         get_next_tok();
  70         ex v = parse_expression();
  71         switch (s) {
  72                 case '-':
  73                         return (new mul(v, *_num_1_p))->setflag(status_flags::dynallocated);
  74                 case '+':
  75                         return v;
  76                 default:
  77                         throw std::invalid_argument(
  78                                         std::string(__func__)
  79                                         + ": invalid unary operator \""
  80                                         + char(s) + "\"");
  81         }
  82 }
  83
  84 /// primary: identifier_expr | number_expr | paren_expr | unary_expr
  85 ex parser::parse_primary()
  86 {
  87         switch (token) {
  88                 case lexer::token_type::identifier:
  89                          return parse_identifier_expr();
  90                 case lexer::token_type::number:
  91                          return parse_number_expr();
  92                 case '(':
  93                          return parse_paren_expr();
  94                 case '-':
  95                          return parse_unary_expr('-');
  96                 case '+':
  97                          return parse_unary_expr('+');
  98                 case lexer::token_type::literal:
  99                          return parse_literal_expr();
 100                 case lexer::token_type::eof:
 101                          bail_out(std::invalid_argument, "got EOF while parsing the expression");
 102                 default:
 103                          bail_out(std::invalid_argument, "unknown token " <<
 104                                 token << " (\"" <<
 105                                 (token ? std::string("") + char(token) : "NULL")
 106                                 << "\")");
 107         }
 108 }
 109
 110 /// expression ::= primary binoprhs
 111 ex parser::parse_expression()
 112 {
 113         ex lhs = parse_primary();
 114         ex res = parse_binop_rhs(0, lhs);
 115         return res;
 116 }
 117
 118 /// number_expr: number
 119 ex parser::parse_number_expr()
 120 {
 121         ex n = numeric(scanner->str.c_str());
 122         get_next_tok(); // consume the number
 123         return n;
 124 }
 125
 126 /// literal_expr: 'I' | 'Pi' | 'Euler' | 'Catalan'
 127 ex parser::parse_literal_expr()
 128 {
 129         if (scanner->str == "I")
 130                 return I;
 131         else if (scanner->str == "Pi")
 132                 return Pi;
 133         else if (scanner->str == "Euler")
 134                 return Euler;
 135         else if (scanner->str == "Catalan")
 136                 return Catalan;
 137         bug("unknown literal: \"" << scanner->str << "\"");
 138 }
 139
 140 ex parser::operator()(std::istream& input)
 141 {
 142         scanner->switch_input(&input);
 143         get_next_tok();
 144         ex ret = parse_expression();
 145         return ret;
 146 }
 147
 148 ex parser::operator()(const std::string& input)
 149 {
 150         std::istringstream is(input);
 151         ex ret = operator()(is);
 152         return ret;
 153 }
 154
 155 int parser::get_next_tok()
 156 {
 157         token = scanner->gettok();
 158         return token;
 159 }
 160
 161 parser::parser(const symtab& syms_, const prototype_table& funcs_,
 162                const bool strict_) : strict(strict_), funcs(funcs_),
 163         syms(syms_)
 164 {
 165         scanner = new lexer();
 166 }
 167
 168 parser::~parser()
 169 {
 170         delete scanner;
 171 }
 172
 173 } // namespace GiNaC