reencode: Factor into separate modules

1 files changed, 67 insertions, 0 deletions

diff --git a/reencode_compactnum.go b/reencode_compactnum.go
new file mode 100644
index 0000000..5da2c54
--- /dev/null
+++ b/reencode_compactnum.go
@@ -0,0 +1,67 @@
+// Copyright (C) 2022-2023  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+package lowmemjson
+
+import (
+	"git.lukeshu.com/go/lowmemjson/internal/jsonparse"
+)
+
+type reEncodeCompactNum struct {
+	out reEncoderModule
+
+	// state
+	fracFirst bool
+	fracZeros int64
+	expZero   bool
+}
+
+var _ reEncoderModule = (*reEncodeCompactNum)(nil)
+
+func (enc *reEncodeCompactNum) PopWriteBarrier() {
+	enc.out.PopWriteBarrier()
+}
+
+func (enc *reEncodeCompactNum) HandleRune(c rune, t jsonparse.RuneType, escape BackslashEscapeMode, stackSize int) error {
+	// trim trailing '0's from the fraction-part, but don't remove all digits
+	switch t {
+	case jsonparse.RuneTypeNumberFracDot:
+		enc.fracFirst = true
+		enc.fracZeros = 0
+	case jsonparse.RuneTypeNumberFracDig:
+		if c == '0' && !enc.fracFirst {
+			enc.fracZeros++
+			return nil
+		}
+		fallthrough
+	default:
+		for enc.fracZeros > 0 {
+			if err := enc.out.HandleRune('0', jsonparse.RuneTypeNumberFracDig, escape, stackSize); err != nil {
+				return err
+			}
+			enc.fracZeros--
+		}
+		enc.fracFirst = false
+	}
+
+	// trim leading '0's from the exponent-part, but don't remove all digits
+	switch t {
+	case jsonparse.RuneTypeNumberExpE, jsonparse.RuneTypeNumberExpSign:
+		enc.expZero = true
+	case jsonparse.RuneTypeNumberExpDig:
+		if c == '0' && enc.expZero {
+			return nil
+		}
+		enc.expZero = false
+	default:
+		if enc.expZero {
+			if err := enc.out.HandleRune('0', jsonparse.RuneTypeNumberFracDig, escape, stackSize); err != nil {
+				return err
+			}
+			enc.expZero = false
+		}
+	}
+
+	return enc.out.HandleRune(c, t, escape, stackSize)
+}