code / tomo

   1 // Parsing logic for binary operators
   2 #include <stdbool.h>
   3 
   4 #include "../ast.h"
   5 #include "../stdlib/util.h"
   6 #include "context.h"
   7 #include "errors.h"
   8 #include "expressions.h"
   9 #include "suffixes.h"
  10 #include "utils.h"
  11 
  12 ast_e match_binary_operator(const char **pos) {
  13     switch (**pos) {
  14     case '+': {
  15         *pos += 1;
  16         return match(pos, "+") ? Concat : Plus;
  17     }
  18     case '-': {
  19         *pos += 1;
  20         if ((*pos)[0] != ' ' && (*pos)[-2] == ' ') // looks like `fn -5`
  21             return Unknown;
  22         return Minus;
  23     }
  24     case '*': *pos += 1; return Multiply;
  25     case '/': *pos += 1; return Divide;
  26     case '^': *pos += 1; return Power;
  27     case '<': {
  28         *pos += 1;
  29         if (match(pos, "=")) return LessThanOrEquals; // "<="
  30         else if (match(pos, ">")) return Compare; // "<>"
  31         else if (match(pos, "<")) {
  32             if (match(pos, "<")) return UnsignedLeftShift; // "<<<"
  33             return LeftShift; // "<<"
  34         } else return LessThan;
  35     }
  36     case '>': {
  37         *pos += 1;
  38         if (match(pos, "=")) return GreaterThanOrEquals; // ">="
  39         if (match(pos, ">")) {
  40             if (match(pos, ">")) return UnsignedRightShift; // ">>>"
  41             return RightShift; // ">>"
  42         }
  43         return GreaterThan;
  44     }
  45     default: {
  46         if (match(pos, "!=")) return NotEquals;
  47         else if (match(pos, "==") && **pos != '=') return Equals;
  48         else if (match_word(pos, "and")) return And;
  49         else if (match_word(pos, "or")) return Or;
  50         else if (match_word(pos, "xor")) return Xor;
  51         else if (match_word(pos, "mod1")) return Mod1;
  52         else if (match_word(pos, "mod")) return Mod;
  53         else if (match_word(pos, "_min_")) return Min;
  54         else if (match_word(pos, "_max_")) return Max;
  55         else return Unknown;
  56     }
  57     }
  58 }
  59 
  60 ast_t *parse_infix_expr(parse_ctx_t *ctx, const char *pos, int min_tightness) {
  61     ast_t *lhs = optional(ctx, &pos, parse_term);
  62     if (!lhs) return NULL;
  63 
  64     int64_t starting_line = get_line_number(ctx->file, pos);
  65     int64_t starting_indent = get_indent(ctx, pos);
  66     spaces(&pos);
  67     for (ast_e op; (op = match_binary_operator(&pos)) != Unknown && op_tightness[op] >= min_tightness; spaces(&pos)) {
  68         ast_t *key = NULL;
  69         if (op == Min || op == Max) {
  70             key = NewAST(ctx->file, pos, pos, Var, .name = (op == Min ? "_min_" : "_max_"));
  71             for (bool progress = true; progress;) {
  72                 ast_t *new_term;
  73                 progress =
  74                     (false || (new_term = parse_index_suffix(ctx, key))
  75                      || (new_term = parse_method_call_suffix(ctx, key)) || (new_term = parse_field_suffix(ctx, key))
  76                      || (new_term = parse_fncall_suffix(ctx, key)) || (new_term = parse_non_optional_suffix(ctx, key)));
  77                 if (progress) key = new_term;
  78             }
  79             if (key && key->tag == Var) key = NULL;
  80             else if (key) pos = key->end;
  81         }
  82 
  83         whitespace(ctx, &pos);
  84         if (get_line_number(ctx->file, pos) != starting_line && get_indent(ctx, pos) < starting_indent)
  85             parser_err(ctx, pos, eol(pos), "I expected this line to be at least as indented than the line above it");
  86 
  87         ast_t *rhs = parse_infix_expr(ctx, pos, op_tightness[op] + 1);
  88         if (!rhs) break;
  89         pos = rhs->end;
  90 
  91         if (op == Min) {
  92             return NewAST(ctx->file, lhs->start, rhs->end, Min, .lhs = lhs, .rhs = rhs, .key = key);
  93         } else if (op == Max) {
  94             return NewAST(ctx->file, lhs->start, rhs->end, Max, .lhs = lhs, .rhs = rhs, .key = key);
  95         } else {
  96             lhs = new (ast_t, .file = ctx->file, .start = lhs->start, .end = rhs->end, .tag = op,
  97                        .__data.Plus.lhs = lhs, .__data.Plus.rhs = rhs);
  98         }
  99     }
 100     return lhs;
 101 }