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else and else-if support.

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This commit is contained in:
Johannes Findeisen 2025-09-14 03:42:11 +02:00
commit 3f21434cd1
7 changed files with 132 additions and 45 deletions
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114
src/parser.c
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@ -629,36 +629,98 @@ static void parse_block(Bytecode *bc, const char *src, size_t len, size_t *pos,
/* at same indent -> parse statement */
if (starts_with(src, len, *pos, "if")) {
*pos += 2;
/* require at least one space before condition if present */
skip_spaces(src, len, pos);
/* condition: a single expression (booleans/ident/number/string) */
if (!emit_expression(bc, src, len, pos)) {
/* no condition -> treat as false */
int ci = bytecode_add_constant(bc, make_int(0));
bytecode_add_instruction(bc, OP_LOAD_CONST, ci);
}
/* end of condition: ignore any trailing until EOL */
skip_to_eol(src, len, pos);
int end_jumps[64];
int end_count = 0;
/* conditional jump over the block */
int jmp_false = bytecode_add_instruction(bc, OP_JUMP_IF_FALSE, 0);
/* parse nested block if next line is indented */
size_t after_if = *pos;
int next_indent = 0;
if (read_line_start(src, len, pos, &next_indent)) {
if (next_indent > current_indent) {
/* parse body at increased indent */
parse_block(bc, src, len, pos, next_indent);
for (;;) {
/* consume 'if' or 'else if' condition */
if (starts_with(src, len, *pos, "if")) {
*pos += 2;
} else {
/* empty if-body; keep *pos at start of that line (already set) */
/* for 'else if' we arrive here with *pos already after 'if' */
}
/* require at least one space before condition if present */
skip_spaces(src, len, pos);
if (!emit_expression(bc, src, len, pos)) {
/* no condition -> treat as false */
int ci = bytecode_add_constant(bc, make_int(0));
bytecode_add_instruction(bc, OP_LOAD_CONST, ci);
}
/* end of condition: ignore any trailing until EOL */
skip_to_eol(src, len, pos);
/* conditional jump over this clause's block */
int jmp_false = bytecode_add_instruction(bc, OP_JUMP_IF_FALSE, 0);
/* parse nested block if next line is indented */
int next_indent = 0;
size_t after_hdr = *pos;
if (read_line_start(src, len, pos, &next_indent)) {
if (next_indent > current_indent) {
/* parse body at increased indent */
parse_block(bc, src, len, pos, next_indent);
} else {
/* empty body; keep *pos at start of that line */
}
} else {
/* EOF -> empty body */
}
/* after body, unconditionally jump to end of the whole chain */
int jmp_end = bytecode_add_instruction(bc, OP_JUMP, 0);
if (end_count < (int)(sizeof(end_jumps) / sizeof(end_jumps[0]))) {
end_jumps[end_count++] = jmp_end;
} else {
parser_fail(*pos, "Too many chained else/if clauses");
return;
}
/* patch false-jump target to start of next clause (or fallthrough) */
bytecode_set_operand(bc, jmp_false, bc->instr_count);
/* look for else or else if at the same indentation */
size_t look = *pos;
int look_indent = 0;
if (!read_line_start(src, len, &look, &look_indent)) {
/* EOF: break and patch end jumps */
break;
}
if (look_indent != current_indent) {
/* dedent or deeper indent means no 'else' clause here */
break;
}
if (starts_with(src, len, look, "else")) {
/* consume 'else' */
*pos = look + 4;
skip_spaces(src, len, pos);
if (starts_with(src, len, *pos, "if")) {
/* else if -> consume 'if' token and continue loop to parse condition */
*pos += 2;
continue;
} else {
/* plain else: parse its block and finish the chain */
skip_to_eol(src, len, pos);
int else_indent = 0;
if (read_line_start(src, len, pos, &else_indent) && else_indent > current_indent) {
parse_block(bc, src, len, pos, else_indent);
} else {
/* empty else-body */
}
/* end of chain after else */
break;
}
} else {
/* next line is not an else/else if */
break;
}
} else {
/* EOF -> empty body */
}
/* patch jump to here */
bytecode_set_operand(bc, jmp_false, bc->instr_count);
/* patch all end-of-clause jumps to the end of the chain */
for (int i = 0; i < end_count; ++i) {
bytecode_set_operand(bc, end_jumps[i], bc->instr_count);
}
continue;
}