reencode: Factor into separate modules

1 files changed, 102 insertions, 0 deletions

diff --git a/reencode_indent.go b/reencode_indent.go
new file mode 100644
index 0000000..90b35db
--- /dev/null
+++ b/reencode_indent.go
@@ -0,0 +1,102 @@
+// 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 reEncodeIndent struct {
+	out reEncoderModule
+
+	// String to use to indent.
+	//
+	// Newlines are emitted *between* top-level values; a newline
+	// is not emitted after the *last* top-level value.
+	Indent string
+
+	// String to put before indents.
+	Prefix string
+
+	// state
+	lastNonSpace       jsonparse.RuneType
+	lastNonSpaceNonEOF jsonparse.RuneType
+	curIndent          int
+}
+
+var _ reEncoderModule = (*reEncodeIndent)(nil)
+
+func (enc *reEncodeIndent) PopWriteBarrier() {
+	enc.lastNonSpace = enc.lastNonSpaceNonEOF
+	enc.out.PopWriteBarrier()
+}
+
+func (enc *reEncodeIndent) HandleRune(c rune, t jsonparse.RuneType, escape BackslashEscapeMode, stackSize int) error {
+	// emit newlines between top-level values
+	if enc.lastNonSpace == jsonparse.RuneTypeEOF && t != jsonparse.RuneTypeSpace {
+		if err := enc.out.HandleRune('\n', jsonparse.RuneTypeSpace, 0, 0); err != nil {
+			return err
+		}
+	}
+
+	// indent
+	switch t {
+	case jsonparse.RuneTypeSpace:
+		// let us manage whitespace, don't pass it through
+		return nil
+	case jsonparse.RuneTypeObjectEnd, jsonparse.RuneTypeArrayEnd:
+		enc.curIndent--
+		switch enc.lastNonSpace {
+		case jsonparse.RuneTypeObjectBeg, jsonparse.RuneTypeArrayBeg:
+			// collapse
+		default:
+			if err := enc.emitNlIndent(stackSize + 1); err != nil {
+				return err
+			}
+		}
+	default:
+		switch enc.lastNonSpace {
+		case jsonparse.RuneTypeObjectBeg, jsonparse.RuneTypeObjectComma, jsonparse.RuneTypeArrayBeg, jsonparse.RuneTypeArrayComma:
+			if err := enc.emitNlIndent(stackSize); err != nil {
+				return err
+			}
+		case jsonparse.RuneTypeObjectColon:
+			if err := enc.out.HandleRune(' ', jsonparse.RuneTypeSpace, 0, stackSize); err != nil {
+				return err
+			}
+		}
+		switch t {
+		case jsonparse.RuneTypeObjectBeg, jsonparse.RuneTypeArrayBeg:
+			enc.curIndent++
+		}
+	}
+
+	if t != jsonparse.RuneTypeSpace {
+		enc.lastNonSpace = t
+		if t != jsonparse.RuneTypeEOF {
+			enc.lastNonSpaceNonEOF = t
+		}
+	}
+	return enc.out.HandleRune(c, t, escape, stackSize)
+}
+
+func (enc *reEncodeIndent) emitNlIndent(stackSize int) error {
+	if err := enc.out.HandleRune('\n', jsonparse.RuneTypeSpace, 0, stackSize); err != nil {
+		return err
+	}
+	for _, c := range enc.Prefix {
+		if err := enc.out.HandleRune(c, jsonparse.RuneTypeSpace, 0, stackSize); err != nil {
+			return err
+		}
+	}
+	for i := 0; i < enc.curIndent; i++ {
+		for _, c := range enc.Indent {
+			if err := enc.out.HandleRune(c, jsonparse.RuneTypeSpace, 0, stackSize); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}