diff options
| author | Bruce Hill <bruce@bruce-hill.com> | 2024-02-22 12:45:12 -0500 |
|---|---|---|
| committer | Bruce Hill <bruce@bruce-hill.com> | 2024-02-22 12:45:12 -0500 |
| commit | 2ecd8e11fd9edc42f8593edf334dc54d3a2d6930 (patch) | |
| tree | f439c1ce77bedea699ad5d7330aebbde56d1da35 /parse.c | |
| parent | d915c5f5a256dcfa80444e0175a327570935b000 (diff) | |
Implement 'when' statement for matching on enums
Diffstat (limited to 'parse.c')
| -rw-r--r-- | parse.c | 52 |
1 files changed, 50 insertions, 2 deletions
@@ -43,7 +43,7 @@ int op_tightness[] = { #define MAX_TIGHTNESS 9 static const char *keywords[] = { - "yes", "xor", "while", "use", "then", "struct", "stop", "skip", "return", + "yes", "xor", "while", "when", "use", "then", "struct", "stop", "skip", "return", "or", "not", "no", "mod1", "mod", "in", "if", "func", "for", "extern", "enum", "else", "do", "and", "_mix_", "_min_", "_max_", NULL, @@ -71,6 +71,7 @@ static arg_ast_t *parse_args(parse_ctx_t *ctx, const char **pos, bool allow_unna static PARSER(parse_for); static PARSER(parse_while); static PARSER(parse_if); +static PARSER(parse_when); static PARSER(parse_expr); static PARSER(parse_extended_expr); static PARSER(parse_term_no_suffix); @@ -803,13 +804,59 @@ PARSER(parse_if) { const char *tmp = pos; whitespace(&tmp); ast_t *else_body = NULL; + const char *else_start = pos; if (get_indent(ctx->file, tmp) == starting_indent && match_word(&tmp, "else")) { pos = tmp; - else_body = expect(ctx, start, &pos, parse_opt_indented_block, "I expected a body for this 'else'"); + else_body = expect(ctx, else_start, &pos, parse_opt_indented_block, "I expected a body for this 'else'"); } return NewAST(ctx->file, start, pos, If, .condition=condition, .body=body, .else_body=else_body); } +PARSER(parse_when) { + // when <expr> (is var : Tag [then] <body>)* [else <body>] + const char *start = pos; + int64_t starting_indent = get_indent(ctx->file, pos); + + if (!match_word(&pos, "when")) + return NULL; + + ast_t *subject = optional(ctx, &pos, parse_declaration); + if (!subject) subject = expect(ctx, start, &pos, parse_expr, + "I expected to find an expression for this 'when'"); + + when_clause_t *clauses = NULL; + const char *tmp = pos; + whitespace(&tmp); + while (get_indent(ctx->file, tmp) == starting_indent && match_word(&tmp, "is")) { + pos = tmp; + spaces(&pos); + ast_t *tag_name, *var = expect(ctx, start, &pos, parse_var, "I expected a variable or tag name here"); + spaces(&pos); + if (match(&pos, ":")) { + spaces(&pos); + tag_name = optional(ctx, &pos, parse_var); + } else { + tag_name = var; + var = NULL; + } + + match_word(&pos, "then"); // optional + ast_t *body = expect(ctx, start, &pos, parse_opt_indented_block, "I expected a body for this 'when' clause"); + clauses = new(when_clause_t, .var=var, .tag_name=tag_name, .body=body, .next=clauses); + tmp = pos; + whitespace(&tmp); + } + REVERSE_LIST(clauses); + + ast_t *else_body = NULL; + const char *else_start = pos; + if (get_indent(ctx->file, tmp) == starting_indent && match_word(&tmp, "else")) { + pos = tmp; + else_body = expect(ctx, else_start, &pos, parse_opt_indented_block, "I expected a body for this 'else'"); + } + return NewAST(ctx->file, start, pos, When, .subject=subject, .clauses=clauses, .else_body=else_body); +} + PARSER(parse_for) { // for [k,] v in iter [<indent>] body const char *start = pos; @@ -1343,6 +1390,7 @@ PARSER(parse_extended_expr) { || (expr=optional(ctx, &pos, parse_for)) || (expr=optional(ctx, &pos, parse_while)) || (expr=optional(ctx, &pos, parse_if)) + || (expr=optional(ctx, &pos, parse_when)) ) return expr; |