Function parse_condition_lhs

src/cypher/cypher.c:1140–1201

Parse the left-hand side of a WHERE condition into c. * Returns CBM_NOT_FOUND on error, 0 when an operator/value should follow, and * COND_LHS_COMPLETE when the condition is already complete (label test). */

 * Returns CBM_NOT_FOUND on error, 0 when an operator/value should follow, and
 * COND_LHS_COMPLETE when the condition is already complete (label test). */
static int parse_condition_lhs(parser_t *p, cbm_condition_t *c) {
    if (is_multiarg_func_call(p)) {
        /* Multi-arg scalar function LHS: coalesce(f.depth, 0) >= 2 (#874).
         * Reuse the RETURN-item parser, then move ownership into the condition. */
        cbm_return_item_t fitem;
        memset(&fitem, 0, sizeof(fitem));
        if (parse_multiarg_func_item(p, &fitem) < 0) {
            func_item_fields_free(&fitem);
            return CBM_NOT_FOUND;
        }
        c->variable = fitem.variable;
        c->property = fitem.property;
        c->func = fitem.func;
        c->args = fitem.args;
        c->arg_count = fitem.arg_count;
        return 0;
    }

    if (check(p, TOK_IDENT) && p->pos + SKIP_ONE < p->count &&
        p->tokens[p->pos + SKIP_ONE].type == TOK_LPAREN) {
        /* Unrecognised function call in WHERE — fail loudly with the supported
         * set instead of the misleading "unexpected operator" (#874). */
        snprintf(p->error, sizeof(p->error),
                 "unsupported function '%s' in WHERE (supported: coalesce, substring, replace, "
                 "left, right)",
                 peek(p)->text);
        return CBM_NOT_FOUND;
    }

    const cbm_token_t *var = expect(p, TOK_IDENT);
    if (!var) {
        return CBM_NOT_FOUND;
    }

    /* Label test: WHERE n:Label (openCypher, #241). Modelled as a leaf with
     * op="HAS_LABEL" and value=Label, evaluated against the bound node's label. */
    if (check(p, TOK_COLON)) {
        advance(p);
        const cbm_token_t *lbl = expect(p, TOK_IDENT);
        if (!lbl) {
            return CBM_NOT_FOUND;
        }
        c->variable = heap_strdup(var->text);
        c->op = heap_strdup("HAS_LABEL");
        c->value = heap_strdup(lbl->text);
        return COND_LHS_COMPLETE;
    }

    if (match(p, TOK_DOT)) {
        const cbm_token_t *prop = expect(p, TOK_IDENT);
        if (!prop) {
            return CBM_NOT_FOUND;
        }
        c->variable = heap_strdup(var->text);
        c->property = heap_strdup(prop->text);
    } else {
        /* No dot: bare alias (e.g. post-WITH variable like "cnt") */
        c->variable = heap_strdup(var->text);