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1 /*
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2 compiler.c
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3
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4 Copyright © 2011 William Astle
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5
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6 This file is part of LWTOOLS.
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7
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8 LWTOOLS is free software: you can redistribute it and/or modify it under the
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9 terms of the GNU General Public License as published by the Free Software
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10 Foundation, either version 3 of the License, or (at your option) any later
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11 version.
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12
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13 This program is distributed in the hope that it will be useful, but WITHOUT
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14 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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16 more details.
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17
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18 You should have received a copy of the GNU General Public License along with
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19 this program. If not, see <http://www.gnu.org/licenses/>.
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20 */
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21
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22 /*
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23 This is the actual compiler bit; it drives the parser and code generation
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24 */
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25
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26 #include <stdio.h>
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27
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28 #include "lwbasic.h"
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29
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30 /* parse a type; the next token will be acquired as a result */
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31 /* the token advancement is to provide consistency */
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32 static int parse_type(cstate *state)
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33 {
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34 int pt = -1;
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35
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36 switch (state -> lexer_token)
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37 {
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38 case token_kw_integer:
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39 pt = 1;
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40 break;
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41
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42 default:
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43 lwb_error("Invalid type specification");
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44 }
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45 lexer(state);
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46 /* look for "unsigned" modifier for integer types */
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47 return pt;
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48 }
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49
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50
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51 /* issub means RETURNS is not allowed; !issub means RETURNS is required */
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52 static void parse_subfunc(cstate *state, int issub)
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53 {
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54 int pt;
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55
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56 lexer(state);
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57 if (state -> lexer_token != token_identifier)
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58 {
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59 lwb_error("Invalid sub name '%s'", state -> lexer_token_string);
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60 }
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61
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62 printf("<name> = %s\n", state -> lexer_token_string);
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63
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64 lexer(state);
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65 if (state -> lexer_token == token_kw_public || state -> lexer_token == token_kw_private)
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66 {
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67 printf("<type> = %s\n", state -> lexer_token_string);
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68 lexer(state);
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69 }
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70
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71 /* ignore the "PARAMS" keyword if present */
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72 if (state -> lexer_token == token_kw_params)
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73 lexer(state);
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74
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75 if (state -> lexer_token == token_eol)
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76 goto noparms;
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77
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78 paramagain:
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79 if (state -> lexer_token != token_identifier)
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80 {
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81 lwb_error("Parameter name expected, get %d, %s\n", state -> lexer_token, state -> lexer_token_string);
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82 }
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83 printf("Got <param> = %s\n", state -> lexer_token_string);
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84 lexer(state);
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85
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86 if (state -> lexer_token != token_kw_as)
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87 lwb_error("Expecting AS\n");
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88 lexer(state);
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89
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90 pt = parse_type(state);
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91 printf("Got <type> = %d\n", pt);
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92
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93 if (state -> lexer_token == token_char && state -> lexer_token_string[0] == ',')
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94 {
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95 lexer(state);
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96 goto paramagain;
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97 }
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98
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99 noparms:
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100 if (!issub)
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101 {
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102 int rt;
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103
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104 if (state -> lexer_token != token_kw_returns)
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105 {
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106 lwb_error("FUNCTION must have RETURNS\n");
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107 }
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108 lexer(state);
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109 if (state -> lexer_token == token_identifier)
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110 {
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111 printf("Return value named: %s\n", state -> lexer_token_string);
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112 lexer(state);
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113 if (state -> lexer_token != token_kw_as)
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114 lwb_error("Execting AS after RETURNS");
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115 lexer(state);
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116 }
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117 rt = parse_type(state);
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118 printf("Return type: %d\n", rt);
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119 }
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120 else
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121 {
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122 if (state -> lexer_token == token_kw_returns)
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123 {
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124 lwb_error("SUB cannot specify RETURNS\n");
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125 }
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126 }
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127
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128
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129 if (state -> lexer_token != token_eol)
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130 {
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131 lwb_error("EOL expected; found %d, %s\n", state -> lexer_token, state -> lexer_token_string);
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132 }
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133 }
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134
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135 void compiler(cstate *state)
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136 {
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137 state -> lexer_curchar = -1;
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138
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139 /* now look for a global declaration */
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140 for (;;)
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141 {
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142 state -> parser_state = parser_state_global;
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143 lexer(state);
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144 switch (state -> lexer_token)
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145 {
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146 case token_kw_function:
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147 printf("Function\n");
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148 parse_subfunc(state, 0);
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149 break;
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150
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151 case token_kw_sub:
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152 printf("Sub\n");
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153 parse_subfunc(state, 1);
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154 break;
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155
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156 /* blank lines are allowed */
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157 case token_eol:
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158 continue;
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159
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160 /* EOF is allowed - end of parsing */
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161 case token_eof:
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162 return;
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163
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164 default:
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165 lwb_error("Invalid token %d, %s in global state\n", state -> lexer_token, state -> lexer_token_string);
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166 }
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167 }
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168 }
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