Merge pull request #3541 from xackus/language_server

* fix json parser crashing on empty input

* make implicit cast of tagged unions to enums easier to find in docs

doc/langref.html.in

@@ -2778,6 +2778,7 @@ test "simple union" {
       This turns the union into a <em>tagged</em> union, which makes it eligible
       to use with {#link|switch#} expressions. One can use {#link|@TagType#} to
       obtain the enum type from the union type.
+      Tagged unions implicitly cast to their enum {#link|Implicit Cast: unions and enums#}
       </p>
       {#code_begin|test#}
 const std = @import("std");
@@ -2805,6 +2806,14 @@ test "switch on tagged union" {
 test "@TagType" {
     assert(@TagType(ComplexType) == ComplexTypeTag);
 }
+
+test "implicit cast to enum" {
+    const c1 = ComplexType{ .Ok = 42 };
+    const c2 = ComplexType.NotOk;
+
+    assert(c1 == .Ok);
+    assert(c2 == .NotOk);
+}
       {#code_end#}
       <p>In order to modify the payload of a tagged union in a switch expression,
       place a {#syntax#}*{#endsyntax#} before the variable name to make it a pointer:

lib/std/json.zig

@@ -867,6 +867,8 @@ pub const TokenStream = struct {
     parser: StreamingParser,
     token: ?Token,
 
+    pub const Error = StreamingParser.Error || error{UnexpectedEndOfJson};
+
     pub fn init(slice: []const u8) TokenStream {
         return TokenStream{
             .i = 0,
@@ -876,7 +878,7 @@ pub const TokenStream = struct {
         };
     }
 
-    pub fn next(self: *TokenStream) !?Token {
+    pub fn next(self: *TokenStream) Error!?Token {
         if (self.token) |token| {
             const copy = token;
             self.token = null;
@@ -896,16 +898,11 @@ pub const TokenStream = struct {
             }
         }
 
-        if (self.i > self.slice.len) {
-            try self.parser.feed(' ', &t1, &t2);
-            self.i += 1;
-
-            if (t1) |token| {
-                return token;
-            }
+        if(self.parser.complete){
+            return null;
+        } else {
+            return error.UnexpectedEndOfJson;
         }
-
-        return null;
     }
 };
 
@@ -1456,3 +1453,9 @@ test "write json then parse it" {
     testing.expect(tree.root.Object.get("array").?.value.Array.at(1).Float == 12.34);
     testing.expect(mem.eql(u8, tree.root.Object.get("str").?.value.String, "hello"));
 }
+
+test "parsing empty string gives appropriate error" {
+    var p = Parser.init(debug.global_allocator, false);
+    defer p.deinit();
+    testing.expectError(error.UnexpectedEndOfJson, p.parse(""));
+}