Merge pull request #4 from rameel/enhancement

Enhancements

* Rename Before parser to ThenIgnore
* Add Tiny-C parser to Samples

Author: rameel

README.md

@@ -22,40 +22,40 @@ private static Parser<double> CreateParser()
 {
     // Grammar:
     // ----------------------------------------
-    // Start       :  Sum $
-    // Sum         :  Product (S [+-] Product)*
-    // Product     :  Unary (S [*/] Unary)*
-    // Unary       :  S '-'? Primary
+    // Start       :  S Sum $
+    // Sum         :  Product ([+-] S Product)*
+    // Product     :  Unary ([*/] S Unary)*
+    // Unary       :  '-'? S Primary
     // Primary     :  Parenthesis / Value
-    // Parenthesis :  S '(' Sum S ')'
-    // Value       :  S Number
-    // S           :  Whitespace*
+    // Parenthesis :  '(' S Sum ')' S
+    // Value       :  Number S
+    // S           :  [ \r\n\t]*
 
     var sum = Deferred<double>();
-    var value = S.Then(Literal.Number<double>());
+    var value = Literal.Number<double>().ThenIgnore(S);
 
     var parenthesis = sum.Between(
-        Seq(S, L('(')),
-        Seq(S, L(')'))
+        Seq(L('('), S),
+        Seq(L(')'), S)
         );
 
     var primary = parenthesis.Or(value);
 
     var unary = Seq(
-        S,
         L('-').Optional(),
+        S,
         primary
-        ).Do((_, u, d) => u.HasValue ? -d : d);
+        ).Do((u, _, d) => u.HasValue ? -d : d);
 
     var product = unary.Fold(
-        S.Then(OneOf("*/")),
+        OneOf("*/").ThenIgnore(S),
         (l, r, op) => op == '*' ? l * r : l / r);
 
     sum.Parser = product.Fold(
-        S.Then(OneOf("+-")),
+        OneOf("+-").ThenIgnore(S),
         (l, r, op) => op == '+' ? l + r : l - r);
 
-    return sum.Before(Eof);
+    return sum.Between(S, Eof);
 }
 ```
 

benchmarks/Parsers/RamstackParsers.cs

@@ -7,8 +7,8 @@ public static class RamstackParsers
 {
     public static readonly Parser<string> EmailParser = CreateEmailParser();
     public static readonly Parser<Unit> EmailVoidParser = EmailParser.Void();
-    public static readonly Parser<double> ExpressionParser = Samples.ExpressionParser.Parser;
-    public static readonly Parser<object?> JsonParser = Samples.JsonParser.Parser;
+    public static readonly Parser<double> ExpressionParser = Samples.CalcExpr.ExpressionParser.Parser;
+    public static readonly Parser<object?> JsonParser = Samples.Json.JsonParser.Parser;
 
     private static Parser<string> CreateEmailParser()
     {

samples/CalcExpr/ExpressionParser.cs

@@ -0,0 +1,49 @@
+using System.Diagnostics.CodeAnalysis;
+
+using Ramstack.Parsing;
+
+using static Ramstack.Parsing.Parser;
+
+namespace Samples.CalcExpr;
+
+public static class ExpressionParser
+{
+    public static readonly Parser<double> Parser = CreateExpressionParser();
+
+    [SuppressMessage("ReSharper", "InconsistentNaming")]
+    private static Parser<double> CreateExpressionParser()
+    {
+        var sum_expr =
+            Deferred<double>();
+
+        var number_expr =
+            Literal.Number<double>("number").ThenIgnore(S);
+
+        var parenthesis_expr =
+            sum_expr.Between(
+                Seq(L('('), S),
+                Seq(L(')'), S));
+
+        var primary_expr =
+            parenthesis_expr.Or(number_expr);
+
+        var unary_expr =
+            Seq(
+                L('-').Optional(),
+                S,
+                primary_expr
+            ).Do((u, _, d) => u.HasValue ? -d : d);
+
+        var mul_expr =
+            unary_expr.Fold(
+                OneOf("*/").ThenIgnore(S),
+                (l, r, o) => o == '*' ? l * r : l / r);
+
+        sum_expr.Parser =
+            mul_expr.Fold(
+                OneOf("+-").ThenIgnore(S),
+                (l, r, o) => o == '+' ? l + r : l - r);
+
+        return sum_expr.Between(S, Eof);
+    }
+}

samples/CalcExpr/README.md

@@ -0,0 +1,43 @@
+# Simple Calc
+
+This project implements a simple mathematical expression parser.
+
+## Simple Expression Grammar
+
+```sh
+start
+  =  sum_expr EOF
+  ;
+
+sum_expr
+  = mul_expr (S [+-] mul_expr)*
+  ;
+
+mul_expr
+  = unary_expr (S [*/] unary_expr)*
+  ;
+
+unary_expr
+  = S "-"? primary_expr
+  ;
+
+primary_expr
+  = parenthesis_expr / number_expr
+  ;
+
+parenthesis_expr
+  = S "(" Sum S ")"
+  ;
+
+number_expr
+  =  S [0-9]+
+  ;
+
+S
+  = [ \t\r\n]*
+  ;
+
+EOF:
+  = $
+  ;
+```

samples/ExpressionParser.cs

@@ -0,0 +1,60 @@
+using Ramstack.Parsing;
+
+using static Ramstack.Parsing.Literal;
+using static Ramstack.Parsing.Parser;
+
+namespace Samples.Json;
+
+public static class JsonParser
+{
+    public static readonly Parser<object?> Parser = CreateJsonParser();
+
+    private static Parser<object?> CreateJsonParser()
+    {
+        var value =
+            Deferred<object?>();
+
+        var @string =
+            DoubleQuotedString.Do(object? (s) => s);
+
+        var number =
+            Number<double>().Do(object? (n) => n);
+
+        var primitive = OneOf(["true", "false", "null"]).Do(s =>
+        {
+            object? r = null;
+            if (s.Length != 0 && s[0] != 'n')
+                r = s[0] == 't';
+            return r;
+        });
+
+        var array = value
+            .Separated(Seq(L(','), S))
+            .Between(
+                Seq(L('['), S),
+                Seq(L(']'), S))
+            .Do(object? (list) => list);
+
+        var member = Seq(
+            DoubleQuotedString, S, L(':'), S, value
+            ).Do((name, _, _, _, v) => KeyValuePair.Create(name, v));
+
+        var @object = member
+            .Separated(Seq(L(','), S))
+            .Between(
+                Seq(L('{'), S),
+                Seq(L('}'), S))
+            .Do(object? (members) => new Dictionary<string, object?>(members));
+
+        value.Parser =
+            Choice(
+                @string,
+                number,
+                primitive,
+                array,
+                @object
+                ).ThenIgnore(S);
+
+        return S.Then(value);
+    }
+}

samples/Json/JsonParser.cs

@@ -0,0 +1,31 @@
+# JSON Parser
+
+This project implements a simple JSON parser.
+
+## JSON Grammar
+
+```sh
+start
+  = value $
+  ;
+
+value
+  = (object / array / string / number / "true" / "false" / "null") S
+  ;
+
+object
+  = "{" S (member ("," S member)*)? "}" S
+  ;
+
+member
+  = string ":" S value
+  ;
+
+array
+  = "[" S (value ("," S value)*)? "]" S
+  ;
+
+S
+  = [ \t\r\n]*
+  ;
+```