Merge branch 'lukeshu/fix'

4 files changed, 96 insertions, 13 deletions

diff --git a/methods_test.go b/methods_test.go
index f5d5a9a..64af28c 100644
--- a/methods_test.go
+++ b/methods_test.go
@@ -30,6 +30,10 @@ type SumRun struct {
 	Sums         ShortSum
 }
 
+func (run SumRun) Size() int64 {
+	return int64(len(run.Sums)/(2*run.ChecksumSize)) * (4 * 1024)
+}
+
 type SumRunWithGaps struct {
 	Addr int64
 	Size int64
@@ -47,13 +51,19 @@ func (sg SumRunWithGaps) EncodeJSON(w io.Writer) error {
 				return err
 			}
 		}
-		if run.Addr > cur {
+		switch {
+		case run.Addr < cur:
+			return fmt.Errorf("invalid %T: addr went backwards: %v < %v", sg, run.Addr, cur)
+		case run.Addr > cur:
 			if _, err := fmt.Fprintf(w, `{"Gap":%d},`, run.Addr-cur); err != nil {
 				return err
 			}
-		}
-		if err := lowmemjson.NewEncoder(w).Encode(run); err != nil {
-			return err
+			fallthrough
+		default:
+			if err := lowmemjson.NewEncoder(w).Encode(run); err != nil {
+				return err
+			}
+			cur = run.Addr + run.Size()
 		}
 	}
 	end := sg.Addr + sg.Size
@@ -110,14 +120,14 @@ func TestMethods(t *testing.T) {
 			{
 				ChecksumSize: 4,
 				Addr:         1095761920,
-				Sums:         "c160817cb5c72bbbe",
+				Sums:         "c160817cb5c72bbb",
 			},
 		},
 	}
 	var buf bytes.Buffer
 	assert.NoError(t, lowmemjson.NewEncoder(&buf).Encode(in))
 	assert.Equal(t,
-		`{"Addr":13631488,"Size":416033783808,"Runs":[{"Gap":1082130432},{"ChecksumSize":4,"Addr":1095761920,"Sums":"c160817cb5c72bbbe"},{"Gap":416033783808}]}`,
+		`{"Addr":13631488,"Size":416033783808,"Runs":[{"Gap":1082130432},{"ChecksumSize":4,"Addr":1095761920,"Sums":"c160817cb5c72bbb"},{"Gap":414951645184}]}`,
 		buf.String())
 	var out SumRunWithGaps
 	assert.NoError(t, lowmemjson.NewDecoder(&buf).Decode(&out))
diff --git a/reencode.go b/reencode.go
index eae80db..b135fb8 100644
--- a/reencode.go
+++ b/reencode.go
@@ -99,13 +99,14 @@ type ReEncoder struct {
 	inputPos int64
 
 	// state: .handleRune
-	lastNonSpace internal.RuneType
-	wasNumber    bool
-	curIndent    int
-	uhex         [4]byte // "\uABCD"-encoded characters in strings
-	fracZeros    int64
-	expZero      bool
-	specu        *speculation
+	lastNonSpace       internal.RuneType
+	lastNonSpaceNonEOF internal.RuneType
+	wasNumber          bool
+	curIndent          int
+	uhex               [4]byte // "\uABCD"-encoded characters in strings
+	fracZeros          int64
+	expZero            bool
+	specu              *speculation
 
 	// state: .pushBarrier and .popBarrier
 	stackInputPos []int64
@@ -295,6 +296,7 @@ func (enc *ReEncoder) popWriteBarrier() {
 	enc.par.PopBarrier()
 	enc.inputPos += enc.stackInputPos[len(enc.stackInputPos)-1]
 	enc.stackInputPos = enc.stackInputPos[:len(enc.stackInputPos)-1]
+	enc.lastNonSpace = enc.lastNonSpaceNonEOF
 }
 
 // internal ////////////////////////////////////////////////////////////////////
@@ -532,6 +534,9 @@ func (enc *ReEncoder) handleRuneMain(c rune, t internal.RuneType) error {
 
 	if t != internal.RuneTypeSpace {
 		enc.lastNonSpace = t
+		if t != internal.RuneTypeEOF {
+			enc.lastNonSpaceNonEOF = t
+		}
 	}
 	return err
 }
diff --git a/roundtrip_test.go b/roundtrip_test.go
new file mode 100644
index 0000000..71ca6d0
--- /dev/null
+++ b/roundtrip_test.go
@@ -0,0 +1,54 @@
+// Copyright (C) 2022-2023  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+package lowmemjson_test
+
+import (
+	"bytes"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"git.lukeshu.com/go/lowmemjson"
+)
+
+type ScanDevicesResult map[string]ScanOneDeviceResult
+
+type ScanOneDeviceResult struct {
+	FoundExtentCSums []SysExtentCSum
+}
+
+type SysExtentCSum struct {
+	Generation int64
+	Sums       SumRun
+}
+
+func TestRoundTrip(t *testing.T) {
+	t.Parallel()
+	dents, err := os.ReadDir(filepath.Join("testdata", "roundtrip"))
+	require.NoError(t, err)
+	for _, dent := range dents {
+		filename := dent.Name()
+		if !strings.HasSuffix(filename, ".json") {
+			continue
+		}
+		t.Run(strings.TrimSuffix(filename, ".json"), func(t *testing.T) {
+			t.Parallel()
+			inBytes, err := os.ReadFile(filepath.Join("testdata", "roundtrip", filename))
+			require.NoError(t, err)
+			var obj ScanDevicesResult
+			require.NoError(t, lowmemjson.NewDecoder(bytes.NewReader(inBytes)).DecodeThenEOF(&obj))
+			var outBytes bytes.Buffer
+			require.NoError(t, lowmemjson.NewEncoder(lowmemjson.NewReEncoder(&outBytes, lowmemjson.ReEncoderConfig{
+				Indent:                "\t",
+				ForceTrailingNewlines: true,
+				CompactIfUnder:        16, //nolint:gomnd // This is what looks nice.
+			})).Encode(obj))
+			require.Equal(t, string(inBytes), outBytes.String())
+		})
+	}
+}
diff --git a/testdata/roundtrip/scandevices.json b/testdata/roundtrip/scandevices.json
new file mode 100644
index 0000000..c62f7df
--- /dev/null
+++ b/testdata/roundtrip/scandevices.json
@@ -0,0 +1,14 @@
+{
+	"dev-1234": {
+		"FoundExtentCSums": [
+			{
+				"Generation": 6596005,
+				"Sums": {
+					"ChecksumSize": 4,
+					"Addr": 52626001920,
+					"Sums": "d69e7384e04333e332f32f8ecfd874ea1ea3f66bd54143f826f740b995105d0e8b2d25a21709109c4930e526a68a89e48d3ebdb6f5191bca3e867eba57110e36d885ca46666168ad782b4fe9af483561"
+				}
+			}
+		]
+	}
+}