#119 - Add support of ternary operator

sys27 · May 28, 2020 · 3736b5f · 3736b5f
1 parent 98cd6bd
commit 3736b5f
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Showing 5 changed files with 38 additions and 0 deletions.
diff --git a/xFunc Grammar.txt b/xFunc Grammar.txt
@@ -6,6 +6,7 @@ statement = unaryAssign
           / def
           / undef
           / if
+          / ternary
           / for
           / while
           / exp
@@ -19,6 +20,7 @@ def = ('def' / 'define') '(' assignmentKey ',' exp ')'
 undef = ('undef' / 'undefine') '(' assignmentKey ')'
 
 if = 'if' '(' conditional ',' exp (',' exp)* ')'
+ternary = conditional '?' exp ':' exp
 for = 'for' '(' statement ',' exp ',' conditional ',' statement ')'
 while = 'while' '(' exp ',' conditional ')'
 

diff --git a/xFunc.Maths/Parser.ExpressionFactory.cs b/xFunc.Maths/Parser.ExpressionFactory.cs
@@ -290,5 +290,8 @@ private IExpression CreateFromKeyword(KeywordToken keywordToken, params IExpress
 
         private IExpression CreateMultiplication(params IExpression[] arguments) =>
             new Mul(arguments);
+
+        private IExpression CreateTernary(IExpression condition, IExpression then, IExpression @else) =>
+            new If(condition, then, @else);
     }
 }
diff --git a/xFunc.Maths/Parser.cs b/xFunc.Maths/Parser.cs
@@ -85,6 +85,7 @@ private IExpression Statement(TokenEnumerator tokenEnumerator)
                    Def(tokenEnumerator) ??
                    Undef(tokenEnumerator) ??
                    If(tokenEnumerator) ??
+                   Ternary(tokenEnumerator) ??
                    For(tokenEnumerator) ??
                    While(tokenEnumerator) ??
                    Expression(tokenEnumerator);
@@ -232,6 +233,26 @@ private IExpression If(TokenEnumerator tokenEnumerator)
             return CreateFromKeyword(@if, condition, then);
         }
 
+        private IExpression Ternary(TokenEnumerator tokenEnumerator)
+        {
+            var condition = ConditionalOperator(tokenEnumerator) ??
+                            throw new ParseException(); // TODO:
+
+            if (!tokenEnumerator.Symbol(SymbolToken.QuestionMark))
+                throw new ParseException(); // TODO:
+
+            var then = Expression(tokenEnumerator) ??
+                       throw new ParseException(); // TODO:
+
+            if (!tokenEnumerator.Symbol(SymbolToken.Colon))
+                throw new ParseException(); // TODO:
+
+            var @else = Expression(tokenEnumerator) ??
+                        throw new ParseException(); // TODO:
+
+            return CreateTernary(condition, then, @else);
+        }
+
         private IExpression For(TokenEnumerator tokenEnumerator)
         {
             var @for = tokenEnumerator.Keyword(KeywordToken.For);

diff --git a/xFunc.Maths/Tokenization/Lexer.cs b/xFunc.Maths/Tokenization/Lexer.cs
@@ -83,6 +83,8 @@ private IToken CreateSymbol(ref ReadOnlyMemory<char> function)
                 ',' => Comma,
                 '∠' => Angle,
                 '°' => Degree,
+                ':' => Colon,
+                '?' => QuestionMark,
                 _ => null,
             };
 

diff --git a/xFunc.Maths/Tokenization/Tokens/SymbolToken.cs b/xFunc.Maths/Tokenization/Tokens/SymbolToken.cs
@@ -71,5 +71,15 @@ private SymbolToken(char symbol)
         /// Gets the '°' token.
         /// </summary>
         public static SymbolToken Degree { get; } = new SymbolToken('°');
+
+        /// <summary>
+        /// Gets the ':' token.
+        /// </summary>
+        public static SymbolToken Colon { get; } = new SymbolToken(':');
+
+        /// <summary>
+        /// Gets the '?' token.
+        /// </summary>
+        public static SymbolToken QuestionMark { get; } = new SymbolToken('?');
     }
 }