Added Try tests

parser_test.go

@@ -5,7 +5,7 @@ package gigaparsec_test
 import (
 	"bytes"
 	"errors"
-	"io"
+	"fmt"
 	"testing"
 
 	"git.codemonkeysoftware.net/b/gigaparsec"
@@ -127,8 +127,32 @@ func TestSatisfy(t *testing.T) {
 	Todo(t)
 }
 
-func Try(t *testing.T) {
+func TestTry(t *testing.T) {
-	Todo(t)
+	type R = ptest.ForcedResult
+	var cases = []struct{ P, TryP R }{
+		{P: R{Succeed: false, Consume: false}, TryP: R{Succeed: false, Consume: false}},
+		{P: R{Succeed: false, Consume: true}, TryP: R{Succeed: false, Consume: false}},
+		{P: R{Succeed: true, Consume: false}, TryP: R{Succeed: true, Consume: false}},
+		{P: R{Succeed: true, Consume: true}, TryP: R{Succeed: true, Consume: true}},
+	}
+	for _, c := range cases {
+		t.Run(fmt.Sprintf("%+v", c.P), func(t *testing.T) {
+			start := gigaparsec.MakeState(gigaparsec.SliceReaderAt[R]{c.P})
+			result, err := gigaparsec.Try(ptest.ForceResult)(start)
+			succeeded, _, _ := result.Status()
+			must.NoError(t, err)
+			test.EqOp(t, c.TryP.Succeed, succeeded)
+			test.EqOp(t, c.TryP.Consume, result.Consumed())
+		})
+	}
+	t.Run("fails on error", func(t *testing.T) {
+		expectedErr := errors.New("it broke")
+		p := gigaparsec.Try(gigaparsec.Match(byte(0)))
+		result, err := p(gigaparsec.MakeState(ptest.ErrReaderAt(expectedErr)))
+		succeeded, _, _ := result.Status()
+		test.ErrorIs(t, err, expectedErr)
+		test.False(t, succeeded)
+	})
 }
 
 func TestLabel(t *testing.T) {
@@ -158,39 +182,19 @@ func TestRepeat(t *testing.T) {
 		}
 	}))
 	t.Run("consumes iff at least one application consumes", rapid.MakeCheck(func(t *rapid.T) {
-		type Token struct {
+		input := rapid.Map(rapid.SliceOfN(rapid.Just(ptest.ForcedResult{Succeed: true}), 0, 100),
-			Consume, Succeed bool
+			func(ts []ptest.ForcedResult) []ptest.ForcedResult { return append(ts, ptest.ForcedResult{}) }).Draw(t, "input")
-		}
-		// p will succeed and consume based on the values in the parsed token.
-		var p gigaparsec.Parser[Token, Token] = func(s gigaparsec.State[Token]) (gigaparsec.Result[Token, Token], error) {
-			buf := make([]Token, 1)
-			_, next, err := s.Read(buf)
-			if errors.Is(err, io.EOF) {
-				return gigaparsec.Fail[Token, Token](false, gigaparsec.MessageEnd(s.Pos())), nil
-			}
-			if err != nil {
-				return gigaparsec.Result[Token, Token]{}, err
-			}
-			tok := buf[0]
-			if tok.Succeed {
-				return gigaparsec.Succeed(tok.Consume, tok, next, gigaparsec.MessageOK(s.Pos())), nil
-			} else {
-				return gigaparsec.Fail[Token, Token](tok.Consume, gigaparsec.MakeMessage(s.Pos(), "false", "true")), nil
-			}
-		}
-
-		input := rapid.Map(rapid.SliceOfN(rapid.Just(Token{Succeed: true}), 0, 100),
-			func(ts []Token) []Token { return append(ts, Token{}) }).Draw(t, "input")
 		consumeAt := rapid.Ptr(rapid.IntRange(0, len(input)-1), true).Draw(t, "consumeAt")
 		if consumeAt != nil {
 			input[*consumeAt].Consume = true
 		}
 		shouldConsume := consumeAt != nil
 
-		result, err := gigaparsec.Repeat(0, p)(gigaparsec.MakeState(gigaparsec.SliceReaderAt[Token](input)))
+		result, err := gigaparsec.Repeat(0, ptest.ForceResult)(gigaparsec.MakeState(gigaparsec.SliceReaderAt[ptest.ForcedResult](input)))
 		must.NoError(t, err)
 		test.EqOp(t, shouldConsume, result.Consumed())
 	}))
+
 	t.Run("does not consume on empty input", func(t *testing.T) {
 		p := gigaparsec.Repeat(0, gigaparsec.Match(0))
 		result, err := p(gigaparsec.MakeState(gigaparsec.SliceReaderAt[int](nil)))

test/helpers.go

@@ -4,6 +4,7 @@
 package test
 
 import (
+	"errors"
 	"io"
 
 	"git.codemonkeysoftware.net/b/gigaparsec"
@@ -34,3 +35,22 @@ func SliceOfN[T any](value T, n int) []T {
 	}
 	return s
 }
+
+type ForcedResult struct{ Succeed, Consume bool }
+
+func ForceResult(state gigaparsec.State[ForcedResult]) (gigaparsec.Result[ForcedResult, struct{}], error) {
+	buf := make([]ForcedResult, 1)
+	_, next, err := state.Read(buf)
+	if errors.Is(err, io.EOF) {
+		return gigaparsec.Fail[ForcedResult, struct{}](false, gigaparsec.MessageEnd(state.Pos())), nil
+	}
+	if err != nil {
+		return gigaparsec.Result[ForcedResult, struct{}]{}, err
+	}
+	tok := buf[0]
+	if tok.Succeed {
+		return gigaparsec.Succeed(tok.Consume, struct{}{}, next, gigaparsec.MessageOK(state.Pos())), nil
+	} else {
+		return gigaparsec.Fail[ForcedResult, struct{}](tok.Consume, gigaparsec.MakeMessage(state.Pos(), "Succeed=false", "Succeed=true")), nil
+	}
+}