Add code

2026-09-11 22:44:59 -04:00 · 2019-01-23 22:52:45 -05:00
parent 3f69ec7987
commit ad50a19057
103 changed files with 5734 additions and 1 deletions
@@ -0,0 +1,84 @@
+using System.Collections.Generic;
+using ScriptConverter.Ast.Expressions;
+using ScriptConverter.Ast.Statements;
+
+namespace ScriptConverter.Parser.Parselets.Statements
+{
+    class SwitchParselet : IStatementParselet
+    {
+        public Statement Parse(ScriptParser parser, ScriptToken token, out bool trailingSemicolon)
+        {
+            trailingSemicolon = false;
+
+            parser.Take(ScriptTokenType.LeftParen);
+
+            var expression = parser.ParseExpression();
+
+            parser.Take(ScriptTokenType.RightParen);
+            parser.Take(ScriptTokenType.LeftBrace);
+
+            var hasDefault = false;
+            var branches = new List<SwitchStatement.Branch>();
+
+            while (!parser.Match(ScriptTokenType.RightBrace))
+            {
+                var conditions = new List<Expression>();
+
+                while (true)
+                {
+                    if (parser.MatchAndTake(ScriptTokenType.Case))
+                    {
+                        var condition = parser.ParseExpression();
+                        conditions.Add(condition);
+
+                        parser.Take(ScriptTokenType.Colon);
+                        continue;
+                    }
+
+                    if (!parser.Match(ScriptTokenType.Default))
+                        break;
+
+                    var defaultToken = parser.Take(ScriptTokenType.Default);
+
+                    if (hasDefault)
+                        throw new CompilerException(defaultToken, "Multiple default labels");
+
+                    conditions.Add(null); // special default condition
+                    hasDefault = true;
+
+                    parser.Take(ScriptTokenType.Colon);
+                }
+
+                if (conditions.Count > 0)
+                {
+                    var block = ParseBlock(parser);
+                    var branch = new SwitchStatement.Branch(conditions, block);
+                    branches.Add(branch);
+                    continue;
+                }
+
+                var errorToken = parser.Peek();
+                throw new CompilerException(errorToken, "Expected Case or Default but found {0}", errorToken);
+            }
+
+            parser.Take(ScriptTokenType.RightBrace);
+
+            return new SwitchStatement(token, parser.Previous, expression, branches);
+        }
+
+        private static BlockStatement ParseBlock(ScriptParser parser)
+        {
+            var statements = new List<Statement>();
+            var start = parser.Peek();
+
+            while (!parser.Match(ScriptTokenType.Case) &&
+                   !parser.Match(ScriptTokenType.Default) &&
+                   !parser.Match(ScriptTokenType.RightBrace))
+            {
+                statements.Add(parser.ParseStatement());
+            }
+
+            return new BlockStatement(start, parser.Previous, statements, true);
+        }
+    }
+}