update for loop syntax

it matches more closely the %% binary operator syntax

See #51

doc/langref.md

@@ -85,7 +85,7 @@ SwitchItem = Expression | (Expression "..." Expression)
 
 WhileExpression = "while" "(" Expression ")" Expression
 
-ForExpression = "for" "(" "Symbol" "," Expression option("," "Symbol") ")" Expression
+ForExpression = "for" "(" Expression ")" option("|" "Symbol" option("," "Symbol") "|") Expression
 
 BoolOrExpression = BoolAndExpression "||" BoolOrExpression | BoolAndExpression
 

src/parser.cpp

@@ -1797,7 +1797,7 @@ static AstNode *ast_parse_symbol(ParseContext *pc, int *token_index) {
 }
 
 /*
-ForExpression : token(For) token(LParen) Symbol token(Comma) Expression option(token(Comma) token(Symbol)) token(RParen) Expression
+ForExpression = "for" "(" Expression ")" option("|" "Symbol" option("," "Symbol") "|") Expression
 */
 static AstNode *ast_parse_for_expr(ParseContext *pc, int *token_index, bool mandatory) {
     Token *token = &pc->tokens->at(*token_index);
@@ -1814,18 +1814,24 @@ static AstNode *ast_parse_for_expr(ParseContext *pc, int *token_index, bool mand
     AstNode *node = ast_create_node(pc, NodeTypeForExpr, token);
 
     ast_eat_token(pc, token_index, TokenIdLParen);
-    node->data.for_expr.elem_node = ast_parse_symbol(pc, token_index);
-    ast_eat_token(pc, token_index, TokenIdComma);
     node->data.for_expr.array_expr = ast_parse_expression(pc, token_index, true);
-
-    Token *comma = &pc->tokens->at(*token_index);
-    if (comma->id == TokenIdComma) {
-        *token_index += 1;
-        node->data.for_expr.index_node = ast_parse_symbol(pc, token_index);
-    }
-
     ast_eat_token(pc, token_index, TokenIdRParen);
 
+    Token *maybe_bar = &pc->tokens->at(*token_index);
+    if (maybe_bar->id == TokenIdBinOr) {
+        *token_index += 1;
+        node->data.for_expr.elem_node = ast_parse_symbol(pc, token_index);
+
+        Token *maybe_comma = &pc->tokens->at(*token_index);
+        if (maybe_comma->id == TokenIdComma) {
+            *token_index += 1;
+
+            node->data.for_expr.index_node = ast_parse_symbol(pc, token_index);
+        }
+
+        ast_eat_token(pc, token_index, TokenIdBinOr);
+    }
+
     node->data.for_expr.body = ast_parse_expression(pc, token_index, true);
 
     normalize_parent_ptrs(node);

std/bootstrap.zig

@@ -25,7 +25,7 @@ fn strlen(ptr: &const u8) -> isize {
 
 fn call_main() -> unreachable {
     var args: [argc][]u8 = undefined;
-    for (arg, args, i) {
+    for (args) |arg, i| {
         const ptr = argv[i];
         args[i] = ptr[0...strlen(ptr)];
     }

std/rand.zig

@@ -59,7 +59,7 @@ pub struct Rand {
     }
 
     fn generate_numbers(r: &Rand) {
-        for (item, r.array, i) {
+        for (r.array) |item, i| {
             const y : u32 = (item & 0x80000000) + (r.array[(i + 1) % ARRAY_SIZE] & 0x7fffffff);
             const untempered : u32 = r.array[(i + 397) % ARRAY_SIZE] ^ (y >> 1);
             r.array[i] = if ((y % 2) == 0) {

std/std.zig

@@ -173,7 +173,7 @@ pub error Overflow;
 pub fn parse_u64(buf: []u8, radix: u8) -> %u64 {
     var x : u64 = 0;
 
-    for (c, buf) {
+    for (buf) |c| {
         const digit = char_to_digit(c);
 
         if (digit > radix) {

std/test_runner.zig

@@ -8,7 +8,7 @@ struct TestFn {
 extern var zig_test_fn_list: []TestFn;
 
 pub fn run_tests() -> %void {
-    for (test_fn, zig_test_fn_list, i) {
+    for (zig_test_fn_list) |test_fn, i| {
         %%stderr.print_str("Test ");
         %%stderr.print_i64(i + 1);
         %%stderr.print_str("/");

test/run_tests.cpp

@@ -1120,20 +1120,20 @@ import "std.zig";
 
 pub fn main(args: [][]u8) -> %void {
     const array = []u8 {9, 8, 7, 6};
-    for (item, array) {
+    for (array) |item| {
         %%stdout.print_u64(item);
         %%stdout.printf("\n");
     }
-    for (item, array, index) {
+    for (array) |item, index| {
         %%stdout.print_i64(index);
         %%stdout.printf("\n");
     }
     const unknown_size: []u8 = array;
-    for (item, unknown_size) {
+    for (unknown_size) |item| {
         %%stdout.print_u64(item);
         %%stdout.printf("\n");
     }
-    for (item, unknown_size, index) {
+    for (unknown_size) |item, index| {
         %%stdout.print_i64(index);
         %%stdout.printf("\n");
     }
@@ -1145,7 +1145,7 @@ import "std.zig";
 
 pub fn main(args: [][]u8) -> %void {
     const fns = []@typeof(fn1) { fn1, fn2, fn3, fn4, };
-    for (f, fns) {
+    for (fns) |f| {
         %%stdout.print_u64(f());
         %%stdout.printf("\n");
     }
@@ -1434,7 +1434,7 @@ export fn main(args: c_int, argv: &&u8) -> c_int {
 
     qsort((&c_void)(array.ptr), c_ulong(array.len), @sizeof(i32), compare_fn);
 
-    for (item, array, i) {
+    for (array) |item, i| {
         if (item != i) {
             abort();
         }

test/self_hosted.zig

@@ -81,7 +81,7 @@ enum AnEnumWithPayload {
 fn continue_in_for_loop() {
     const array = []i32 {1, 2, 3, 4, 5};
     var sum : i32 = 0;
-    for (x, array) {
+    for (array) |x| {
         sum += x;
         if (x < 3) {
             continue;