parse: implement parsing of function definitions

bshell/parse/syntax/func.c

@@ -0,0 +1,85 @@
+#include "../syntax.h"
+
+bool parse_func(struct parse_ctx *ctx, struct ast_node **out)
+{
+	if (!parse_keyword(ctx, KW_FUNC)) {
+		return false;
+	}
+
+	struct lex_token *name = NULL;
+	if (!parse_word(ctx, &name)) {
+		report_error(ctx, "expected function identifier");
+		return false;
+	}
+
+	struct func_ast_node *func
+		= (struct func_ast_node *)ast_node_create(AST_FUNC);
+	if (!func) {
+		ctx->p_status = BSHELL_ERR_NO_MEMORY;
+		lex_token_destroy(name);
+		return false;
+	}
+
+	func->n_name = name;
+
+	if (!parse_symbol(ctx, SYM_LEFT_PAREN)) {
+		report_error(ctx, "expected `(` after function identifier");
+		ast_node_destroy((struct ast_node *)func);
+		return false;
+	}
+
+	size_t nr_args = 0;
+	bool ok = true;
+	while (1) {
+		if (parse_symbol(ctx, SYM_RIGHT_PAREN)) {
+			break;
+		}
+
+		if (nr_args > 0 && !parse_symbol(ctx, SYM_COMMA)) {
+			report_error(
+				ctx,
+				"expected `,` or `)` after parameter name");
+			ok = false;
+			break;
+		}
+
+		struct lex_token *param_token = NULL;
+		struct var_ast_node *param_node = NULL;
+		if (!parse_var(ctx, &param_token)) {
+			report_error(ctx, "expected parameter variable");
+			ok = false;
+			break;
+		}
+
+		param_node = (struct var_ast_node *)ast_node_create(AST_VAR);
+		if (!param_node) {
+			ok = false;
+			ctx->p_status = BSHELL_ERR_NO_MEMORY;
+			lex_token_destroy(param_token);
+			break;
+		}
+
+		param_node->n_ident = param_token;
+		fx_queue_push_back(
+			&func->n_params,
+			&param_node->n_base.n_entry);
+	}
+
+	if (!ok) {
+		if (ctx->p_status == BSHELL_SUCCESS) {
+			ctx->p_status = BSHELL_ERR_BAD_SYNTAX;
+		}
+
+		ast_node_destroy((struct ast_node *)func);
+		return false;
+	}
+
+	if (!parse_block(ctx, &func->n_body)) {
+		report_error(ctx, "failed to parse function body");
+		ast_node_destroy((struct ast_node *)func);
+		return false;
+	}
+
+	*out = (struct ast_node *)func;
+	return true;
+}

bshell/parse/syntax/keyword.c

@@ -0,0 +1,21 @@
+#include "../syntax.h"
+
+bool peek_keyword_expr(struct parse_ctx *ctx)
+{
+	return peek_unknown_keyword(ctx) != KW_NONE;
+}
+
+bool parse_keyword_expr(struct parse_ctx *ctx, struct ast_node **out)
+{
+	switch (peek_unknown_keyword(ctx)) {
+	case KW_NONE:
+		return false;
+	case KW_IF:
+		return parse_if(ctx, out);
+	case KW_FUNC:
+		return parse_func(ctx, out);
+	default:
+		ctx->p_status = BSHELL_ERR_BAD_SYNTAX;
+		return false;
+	}
+}