From 8fe464f2563ac35f7894041783debe0dfe82d528 Mon Sep 17 00:00:00 2001
From: Luke Shumaker <lukeshu@datawire.io>
Date: Wed, 17 Aug 2022 17:36:56 -0600
Subject: reencode: Split handleRune in to pre- and post- parts

---
 reencode.go | 102 ++++++++++++++++++++++++++++++++++--------------------------
 1 file changed, 58 insertions(+), 44 deletions(-)

diff --git a/reencode.go b/reencode.go
index 4c62cfc..ead7572 100644
--- a/reencode.go
+++ b/reencode.go
@@ -163,31 +163,30 @@ rehandle:
 // internal ////////////////////////////////////////////////////////////////////
 
 func (enc *ReEncoder) handleRune(c rune, t RuneType) error {
-	// whitespace
-	switch t {
-	case RuneTypeSpace:
-		if enc.Compact || enc.Indent != "" {
-			return nil
-		}
+	err, shouldHandle := enc.handleRunePre(c, t)
+	if err != nil {
+		return err
 	}
+	if !shouldHandle {
+		return nil
+	}
+	return enc.handleRuneMain(c, t)
+}
 
-	defer func() {
-		enc.lastNonSpace = t
-	}()
-
+// handle buffered things that need to happen before the new rune
+// itself is handled.
+func (enc *ReEncoder) handleRunePre(c rune, t RuneType) (error, bool) {
 	// emit newlines between top-level values
 	if enc.lastNonSpace == RuneTypeEOF {
 		switch {
 		case enc.wasNumber && t.IsNumber():
 			if err := enc.emitByte('\n'); err != nil {
-				return err
+				return err, false
 			}
 		case enc.Indent != "" && !enc.Compact:
 			if err := enc.emitByte('\n'); err != nil {
-				return err
+				return err, false
 			}
-		default:
-			// do nothing
 		}
 	}
 
@@ -198,13 +197,13 @@ func (enc *ReEncoder) handleRune(c rune, t RuneType) error {
 	case RuneTypeNumberFracDig:
 		if c == '0' && enc.lastNonSpace == RuneTypeNumberFracDig {
 			enc.fracZeros++
-			return nil
+			return nil, false
 		}
 		fallthrough
 	default:
 		for enc.fracZeros > 0 {
 			if err := enc.emitByte('0'); err != nil {
-				return err
+				return err, false
 			}
 			enc.fracZeros--
 		}
@@ -214,49 +213,67 @@ func (enc *ReEncoder) handleRune(c rune, t RuneType) error {
 		enc.expZero = true
 	case RuneTypeNumberExpDig:
 		if c == '0' && enc.expZero {
-			return nil
+			return nil, false
 		}
 		enc.expZero = false
 	default:
 		if enc.expZero {
 			if err := enc.emitByte('0'); err != nil {
-				return err
+				return err, false
 			}
 			enc.expZero = false
 		}
 	}
 
-	// indent
-	switch t {
-	case RuneTypeObjectBeg, RuneTypeArrayBeg:
-		enc.curIndent++
-	case RuneTypeObjectEnd, RuneTypeArrayEnd:
-		enc.curIndent--
-		switch enc.lastNonSpace {
+	// whitespace
+	switch {
+	case enc.Compact:
+		if t == RuneTypeSpace {
+			return nil, false
+		}
+	case enc.Indent != "":
+		switch t {
+		case RuneTypeSpace:
+			// let us manage whitespace
+			return nil, false
 		case RuneTypeObjectBeg, RuneTypeArrayBeg:
-			// collapse
-		default:
-			if err := enc.emitNlIndent(); err != nil {
-				return err
+			enc.curIndent++
+		case RuneTypeObjectEnd, RuneTypeArrayEnd:
+			enc.curIndent--
+			switch enc.lastNonSpace {
+			case RuneTypeObjectBeg, RuneTypeArrayBeg:
+				// collapse
+			default:
+				if err := enc.emitNlIndent(); err != nil {
+					return err, false
+				}
 			}
-		}
-	case RuneTypeObjectColon:
-		if !enc.Compact && enc.Indent != "" {
-			if err := enc.emitByte(':'); err != nil {
-				return err
+		default:
+			switch enc.lastNonSpace {
+			case RuneTypeObjectBeg, RuneTypeObjectComma, RuneTypeArrayBeg, RuneTypeArrayComma:
+				if err := enc.emitNlIndent(); err != nil {
+					return err, false
+				}
 			}
-			return enc.emitByte(' ')
 		}
-	default:
-		switch enc.lastNonSpace {
-		case RuneTypeObjectBeg, RuneTypeObjectComma, RuneTypeArrayBeg, RuneTypeArrayComma:
-			if err := enc.emitNlIndent(); err != nil {
-				return err
+		if enc.lastNonSpace == RuneTypeObjectColon {
+			if err := enc.emitByte(' '); err != nil {
+				return err, false
 			}
 		}
 	}
 
-	// main
+	return nil, true
+}
+
+// handle the new rune itself, not buffered things
+func (enc *ReEncoder) handleRuneMain(c rune, t RuneType) error {
+	defer func() {
+		if t != RuneTypeSpace {
+			enc.lastNonSpace = t
+		}
+	}()
+
 	switch t {
 
 	case RuneTypeStringChar:
@@ -333,9 +350,6 @@ func (enc *ReEncoder) emit(n int, err error) error {
 }
 
 func (enc *ReEncoder) emitNlIndent() error {
-	if enc.Compact || enc.Indent == "" {
-		return nil
-	}
 	if err := enc.emitByte('\n'); err != nil {
 		return err
 	}
-- 
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