add '\' escape sequence

Author: LytixDev

docs/syntax.md

@@ -11,7 +11,9 @@ var func return if elif else loop in true false as and or not str num bool list
 
 numbers: Can start with 0x (base16), 0b (base2) or nothing (base10) denoting the base. Then a set of number characters valid for the particular base in addition to '-' as a visual seperator. Base ten numbers can also have a decimal point.
 
-string: "" any characters enclosed inside double-qoutes
+string:
+    - "" any characters enclosed inside double-qoutes. Hanldes escape sequences (for example \n becomes newline).
+    - '' any characters enclosed inside single-qoutes Does not hanlde escape sequences.
 
 identifiers: Must start with a letter (a, b, .. z), underscore (_) or hyphen (-). Can then be any sequence of the aformentioned characters plus any number character (0, 1, .. 9).
 

src/interpreter/ast.c

@@ -234,11 +234,16 @@ Stmt *stmt_copy(Arena *arena, Stmt *to_copy)
     }
     case STMT_CMD: {
 	((CmdStmt *)copy)->cmd_name = str_view_arena_copy(arena, ((CmdStmt *)to_copy)->cmd_name);
-	((CmdStmt *)copy)->arg_exprs = arena_ll_alloc(arena);
-	LLItem *item;
-	ARENA_LL_FOR_EACH(((CmdStmt *)to_copy)->arg_exprs, item)
-	{
-	    arena_ll_append(((CmdStmt *)copy)->arg_exprs, expr_copy(arena, item->value));
+
+	if (((CmdStmt *)to_copy)->arg_exprs == NULL) {
+	    ((CmdStmt *)copy)->arg_exprs = NULL;
+	} else {
+	    ((CmdStmt *)copy)->arg_exprs = arena_ll_alloc(arena);
+	    LLItem *item;
+	    ARENA_LL_FOR_EACH(((CmdStmt *)to_copy)->arg_exprs, item)
+	    {
+		arena_ll_append(((CmdStmt *)copy)->arg_exprs, expr_copy(arena, item->value));
+	    }
 	}
 	break;
     }

src/interpreter/lexer.c

@@ -558,6 +558,9 @@ StateFn lex_string(Lexer *lexer)
 	    case 'n':
 		str_builder_append_char(&sb, '\n');
 		break;
+	    case '\\':
+		str_builder_append_char(&sb, '\\');
+		break;
 	    default:
 		report_lex_err(lexer, true, "Unknown escape sequence");
 		/* Error occured. Continue parsing after string is terminated. */

test/str.slash

@@ -7,25 +7,8 @@
     # $a[0] = "H"
     # assert $a[0] == "H"
     # item in
-    # assert ("Hello" in $a) and ("World!" in $a)
 }
 
-# test every method
-# {
-#     var a = "a,b,c"
-#     var res = $a.split(",")
-#     assert $res.len() == 3
-#     assert $res[0] == "a" and $res[1] == "b" and $res[2] == "c"
-# 
-#     $a = "a!!b!!c!!"
-#     $res = $a.split("!!")
-#     assert $res.len() == 3
-#     assert $res[0] == "a" and $res[1] == "b" and $res[2] == "c"
-# }
-
-assert "hello"\
-       "world" == "helloworld"
-
 # string comparison
 assert "hello" == "hello"
 assert "b" > "a"
@@ -40,3 +23,12 @@ assert "something is true"
 assert "Hello" in "Hello World"
 assert not ("Foo" in "Bar")
 assert "" in "something"
+
+# multiline string 
+assert "hello"\
+       "world" == "helloworld"
+
+# escape sequences
+assert '\n' != "\n" # "\n" becomes newline
+assert '\n' == ("\\" + "n") # does not become newline
+assert '\' == "\\"