From 64d998474dc4e0c27b6f9ffa054a556d90ff7d36 Mon Sep 17 00:00:00 2001
From: Jo-Philipp Wich <jo@mein.io>
Date: Mon, 21 Sep 2020 12:50:14 +0200
Subject: syntax: introduce try/catch blocks

Signed-off-by: Jo-Philipp Wich <jo@mein.io>
---
 eval.c   | 25 +++++++++++++++++++++++++
 lexer.c  |  4 ++++
 lexer.h  |  2 +-
 parser.y |  9 +++++++++
 4 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/eval.c b/eval.c
index 13e5c21..0728ba2 100644
--- a/eval.c
+++ b/eval.c
@@ -1435,6 +1435,28 @@ ut_execute_this(struct ut_state *state, uint32_t off)
 	return json_object_get(ut_getproto(ut_getscope(state, 0)));
 }
 
+static struct json_object *
+ut_execute_try_catch(struct ut_state *state, uint32_t off)
+{
+	struct ut_op *op = ut_get_op(state, off);
+	struct json_object *rv;
+
+	rv = ut_execute_op_sequence(state, op->tree.operand[0]);
+
+	if (ut_is_type(rv, T_EXCEPTION)) {
+		if (op->tree.operand[1])
+			ut_putval(ut_setval(ut_getscope(state, 0), ut_get_child(state, off, 1)->val,
+			                    json_object_new_string(json_object_get_string(rv))));
+
+		memset(&state->error, 0, sizeof(state->error));
+
+		ut_putval(rv);
+		rv = ut_execute_op_sequence(state, op->tree.operand[2]);
+	}
+
+	return rv;
+}
+
 static struct json_object *
 ut_execute_op(struct ut_state *state, uint32_t off)
 {
@@ -1594,6 +1616,9 @@ ut_execute_op(struct ut_state *state, uint32_t off)
 	case T_CONTINUE:
 		return ut_execute_break_cont(state, off);
 
+	case T_TRY:
+		return ut_execute_try_catch(state, off);
+
 	default:
 		return ut_exception(state, off, "Runtime error: Unrecognized opcode %d", op->type);
 	}
diff --git a/lexer.c b/lexer.c
index 390a12e..5c1b759 100644
--- a/lexer.c
+++ b/lexer.c
@@ -132,12 +132,14 @@ static const struct token reserved_words[] = {
 	{ T_ENDIF,		"endif", 5 },
 	{ T_WHILE,		"while", 5 },
 	{ T_BREAK,		"break", 5 },
+	{ T_CATCH,		"catch", 5 },
 	{ T_BOOL,		"false", 5, parse_bool },
 	{ T_BOOL,		"true",  4, parse_bool },
 	{ T_ELSE,		"else",  4 },
 	{ T_THIS,		"this",  4 },
 	{ T_NULL,		"null",  4 },
 	{ T_NUMBER,		"NaN",   3, parse_number },
+	{ T_TRY,		"try",   3 },
 	{ T_FOR,		"for",   3 },
 	{ T_IN,			"in",    2 },
 };
@@ -214,6 +216,8 @@ const char *tokennames[__T_MAX] = {
 	[T_CONTINUE]    = "'continue'",
 	[T_NULL]		= "'null'",
 	[T_THIS]        = "'this'",
+	[T_TRY]         = "'try'",
+	[T_CATCH]       = "'catch'",
 	//[T_LSTM]		= "'{%'",
 	//[T_RSTM]		= "'%}'"
 };
diff --git a/lexer.h b/lexer.h
index cb6bca9..06a0ceb 100644
--- a/lexer.h
+++ b/lexer.h
@@ -19,7 +19,7 @@
 
 #include "ast.h"
 
-#define __T_MAX 73
+#define __T_MAX 75
 #define T_EXCEPTION	(__T_MAX + 0)
 #define T_CFUNC		(__T_MAX + 1)
 #define T_RESSOURCE	(__T_MAX + 2)
diff --git a/parser.y b/parser.y
index a3ba991..be59abb 100644
--- a/parser.y
+++ b/parser.y
@@ -114,6 +114,7 @@ stmt(A) ::= exp_stmt(B).								{ A = B; }
 stmt(A) ::= sel_stmt(B).								{ A = B; }
 stmt(A) ::= iter_stmt(B).								{ A = B; }
 stmt(A) ::= func_stmt(B).								{ A = B; }
+stmt(A) ::= try_stmt(B).								{ A = B; }
 stmt(A) ::= ret_stmt(B).								{ A = B; }
 stmt(A) ::= break_stmt(B).								{ A = B; }
 stmt(A) ::= decl_stmt(B).								{ A = B; }
@@ -165,6 +166,14 @@ func_stmt(A) ::= T_FUNC(B) T_LABEL(C) T_LPAREN args(D) T_RPAREN empty_object.
 func_stmt(A) ::= T_FUNC(B) T_LABEL(C) T_LPAREN args(D) T_RPAREN T_COLON chunks(E) T_ENDFUNC.
 														{ A = wrap_op(B, C, D, E); }
 
+try_stmt(A) ::= T_TRY(B) try_catch_block(C) T_CATCH T_LPAREN T_LABEL(D) T_RPAREN try_catch_block(E).
+														{ A = wrap_op(B, C, D, E); }
+try_stmt(A) ::= T_TRY(B) try_catch_block(C) T_CATCH try_catch_block(D).
+														{ A = wrap_op(B, C, 0, D); }
+
+try_catch_block(A) ::= cpd_stmt(B).						{ A = B; }
+try_catch_block(A) ::= empty_object.					{ A = 0; }
+
 args(A) ::= args(B) T_COMMA T_LABEL(C).					{ A = append_op(B, C); }
 args(A) ::= T_LABEL(B).									{ A = B; }
 
-- 
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