Improve readability of json parser code

json/filter.go

@@ -6,7 +6,6 @@ import (
 )
 
 func Filter(w *bytes.Buffer, b []byte, keys []string) error {
-	s := 0
 	state := expectKey
 	var err error
 
@@ -19,10 +18,29 @@ func Filter(w *bytes.Buffer, b []byte, keys []string) error {
 		}
 	}
 
+	// is an list
 	isList := false
+
+	// list item
 	item := 0
+
+	// field in an object
 	field := 0
+
+	s, e, d := 0, 0, 0
+
+	kf := false
+
 	for i := 0; i < len(b); i++ {
+		if state == expectObjClose || state == expectListClose {
+			switch b[i] {
+			case '{', '[':
+				d++
+			case '}', ']':
+				d--
+			}
+		}
+
 		switch {
 		case state == expectKey:
 			switch b[i] {
@@ -35,7 +53,7 @@ func Filter(w *bytes.Buffer, b []byte, keys []string) error {
 				if item == 0 {
 					err = w.WriteByte('{')
 				} else {
-					_, err = w.WriteString("},{")
+					_, err = w.Write([]byte("},{"))
 				}
 				item++
 				field = 0
@@ -44,115 +62,98 @@ func Filter(w *bytes.Buffer, b []byte, keys []string) error {
 				s = i
 				i++
 			}
+			if err != nil {
+				return err
+			}
 		case state == expectKeyClose && b[i] == '"':
 			state = expectColon
-			i++
+			k := b[(s + 1):i]
+			_, kf = kmap[sha1.Sum(k)]
+
+		case state == expectColon && b[i] == ':':
+			state = expectValue
+
+		case state == expectValue && b[i] == '"':
+			state = expectString
+
+		case state == expectString && b[i] == '"':
+			e = i
+
+		case state == expectValue && b[i] == '[':
+			state = expectListClose
+			d++
+
+		case state == expectListClose && d == 0 && b[i] == ']':
+			e = i
+
+		case state == expectValue && b[i] == '{':
+			state = expectObjClose
+			d++
+
+		case state == expectObjClose && d == 0 && b[i] == '}':
+			e = i
+
+		case state == expectValue && (b[i] >= '0' && b[i] <= '9'):
+			state = expectNumClose
+
+		case state == expectNumClose &&
+			((b[i] < '0' || b[i] > '9') &&
+				(b[i] != '.' && b[i] != 'e' && b[i] != 'E' && b[i] != '+' && b[i] != '-')):
+			i--
+			e = i
+
+		case state == expectValue &&
+			(b[i] == 'f' || b[i] == 'F' || b[i] == 't' || b[i] == 'T'):
+			state = expectBoolClose
+
+		case state == expectBoolClose && (b[i] == 'e' || b[i] == 'E'):
+			e = i
 		}
 
-		if err != nil {
+		if e != 0 {
-			return nil
+			state = expectKey
-		}
+			cb := b[s:(e + 1)]
+			e = 0
 
-		if state != expectColon {
+			if !kf {
-			continue
+				continue
-		}
+			}
 
-		k := b[(s + 1):(i - 1)]
+			if field != 0 {
-		h := sha1.Sum(k)
+				if err := w.WriteByte(','); err != nil {
-		_, kf := kmap[h]
+					return err
-
-		e := 0
-		d := 0
-		for ; i < len(b); i++ {
-			if state == expectObjClose || state == expectListClose {
-				switch b[i] {
-				case '{', '[':
-					d++
-				case '}', ']':
-					d--
 				}
 			}
 
-			switch {
+			sk := 0
-			case state == expectColon && b[i] == ':':
+			for i := 0; i < len(cb); i++ {
-				state = expectValue
+				if cb[i] == '\n' || cb[i] == '\t' {
-
+					if _, err := w.Write(cb[sk:i]); err != nil {
-			case state == expectValue && b[i] == '"':
-				state = expectString
-
-			case state == expectString && b[i] == '"':
-				e = i
-
-			case state == expectValue && b[i] == '[':
-				state = expectListClose
-				d++
-
-			case state == expectListClose && d == 0 && b[i] == ']':
-				e = i
-
-			case state == expectValue && b[i] == '{':
-				state = expectObjClose
-				d++
-
-			case state == expectObjClose && d == 0 && b[i] == '}':
-				e = i
-
-			case state == expectValue && (b[i] >= '0' && b[i] <= '9'):
-				state = expectNumClose
-
-			case state == expectNumClose &&
-				((b[i] < '0' || b[i] > '9') &&
-					(b[i] != '.' && b[i] != 'e' && b[i] != 'E' && b[i] != '+' && b[i] != '-')):
-				i--
-				e = i
-
-			case state == expectValue &&
-				(b[i] == 'f' || b[i] == 'F' || b[i] == 't' || b[i] == 'T'):
-				state = expectBoolClose
-
-			case state == expectBoolClose && (b[i] == 'e' || b[i] == 'E'):
-				e = i
-			}
-
-			if e != 0 {
-				if kf {
-					if field != 0 {
-						if err := w.WriteByte(','); err != nil {
-							return err
-						}
-					}
-
-					cb := b[s:(e + 1)]
-					sk := 0
-					for i := 0; i < len(cb); i++ {
-						if cb[i] == '\n' || cb[i] == '\t' {
-							if _, err := w.Write(cb[sk:i]); err != nil {
-								return err
-							}
-							sk = i + 1
-						}
-					}
-
-					if sk > 0 && sk < len(cb) {
-						_, err = w.Write(cb[sk:len(cb)])
-					} else {
-						_, err = w.Write(cb)
-					}
-					if err != nil {
 						return err
 					}
-					field++
+					sk = i + 1
 				}
-				state = expectKey
-				break
 			}
+
+			if sk > 0 && sk < len(cb) {
+				_, err = w.Write(cb[sk:len(cb)])
+			} else {
+				_, err = w.Write(cb)
+			}
+
+			if err != nil {
+				return err
+			}
+			field++
 		}
 	}
+
 	if item != 0 {
 		if err := w.WriteByte('}'); err != nil {
 			return err
 		}
 	}
+
 	if isList {
 		if err := w.WriteByte(']'); err != nil {
 			return err

json/get.go

@@ -34,104 +34,93 @@ func Get(b []byte, keys [][]byte) []Field {
 		}
 	}
 
-	l := 10
+	prealloc := 20
-	res := make([]Field, l)
+	res := make([]Field, prealloc)
+
+	s, e, d := 0, 0, 0
+
+	var kf bool
+	var k []byte
 
 	for i := 0; i < len(b); i++ {
+		if state == expectObjClose || state == expectListClose {
+			switch b[i] {
+			case '{', '[':
+				d++
+			case '}', ']':
+				d--
+			}
+		}
+
 		switch {
 		case state == expectKey && b[i] == '"':
 			state = expectKeyClose
-			s = i + 1
+			s = i
-			continue
 
 		case state == expectKeyClose && b[i] == '"':
 			state = expectColon
+			k = b[(s + 1):i]
+			_, kf = kmap[sha1.Sum(k)]
+
+		case state == expectColon && b[i] == ':':
+			state = expectValue
+
+		case state == expectValue && b[i] == '"':
+			state = expectString
+			s = i
+
+		case state == expectString && b[i] == '"':
+			e = i
+
+		case state == expectValue && b[i] == '[':
+			state = expectListClose
+			s = i
+			d++
+
+		case state == expectListClose && d == 0 && b[i] == ']':
+			e = i
+			i = s
+
+		case state == expectValue && b[i] == '{':
+			state = expectObjClose
+			s = i
+			d++
+
+		case state == expectObjClose && d == 0 && b[i] == '}':
+			e = i
+			i = s
+
+		case state == expectValue && (b[i] >= '0' && b[i] <= '9'):
+			state = expectNumClose
+			s = i
+
+		case state == expectNumClose &&
+			((b[i] < '0' || b[i] > '9') &&
+				(b[i] != '.' && b[i] != 'e' && b[i] != 'E' && b[i] != '+' && b[i] != '-')):
+			i--
+			e = i
+
+		case state == expectValue &&
+			(b[i] == 'f' || b[i] == 'F' || b[i] == 't' || b[i] == 'T'):
+			state = expectBoolClose
+			s = i
+
+		case state == expectBoolClose && (b[i] == 'e' || b[i] == 'E'):
+			e = i
 		}
 
-		if state != expectColon {
+		if e != 0 {
-			continue
+			if kf {
-		}
+				if len(res) == cap(res) {
-
+					r := make([]Field, 0, (len(res) * 2))
-		k := b[s:i]
+					copy(r, res)
-		h := sha1.Sum(k)
+					res = r
-		_, kf := kmap[h]
-
-		e := 0
-		d := 0
-		for ; i < len(b); i++ {
-			if state == expectObjClose || state == expectListClose {
-				switch b[i] {
-				case '{', '[':
-					d++
-				case '}', ']':
-					d--
 				}
+				res = append(res, Field{k, b[s:(e + 1)]})
 			}
 
-			switch {
+			state = expectKey
-			case state == expectColon && b[i] == ':':
+			e = 0
-				state = expectValue
-
-			case state == expectValue && b[i] == '"':
-				state = expectString
-				s = i
-
-			case state == expectString && b[i] == '"':
-				e = i
-
-			case state == expectValue && b[i] == '[':
-				state = expectListClose
-				s = i
-				d++
-
-			case state == expectListClose && d == 0 && b[i] == ']':
-				e = i
-				i = s
-
-			case state == expectValue && b[i] == '{':
-				state = expectObjClose
-				s = i
-				d++
-
-			case state == expectObjClose && d == 0 && b[i] == '}':
-				e = i
-				i = s
-
-			case state == expectValue && (b[i] >= '0' && b[i] <= '9'):
-				state = expectNumClose
-				s = i
-
-			case state == expectNumClose &&
-				((b[i] < '0' || b[i] > '9') &&
-					(b[i] != '.' && b[i] != 'e' && b[i] != 'E' && b[i] != '+' && b[i] != '-')):
-				i--
-				e = i
-
-			case state == expectValue &&
-				(b[i] == 'f' || b[i] == 'F' || b[i] == 't' || b[i] == 'T'):
-				state = expectBoolClose
-				s = i
-
-			case state == expectBoolClose && (b[i] == 'e' || b[i] == 'E'):
-				e = i
-			}
-
-			if e != 0 {
-				e++
-
-				if kf {
-					if len(res) == cap(res) {
-						r := make([]Field, 0, (len(res) + l))
-						copy(r, res)
-						res = r
-					}
-
-					res = append(res, Field{k, b[s:e]})
-				}
-
-				state = expectKey
-				break
-			}
 		}
 	}
 

json/replace.go

@@ -11,12 +11,6 @@ func Replace(w *bytes.Buffer, b []byte, from, to []Field) error {
 		return errors.New("'from' and 'to' must be of the same length")
 	}
 
-	state := expectKey
-	ws, we := 0, len(b)
-
-	s := 0
-	fi := -1
-
 	fmap := make(map[[20]byte]int, (len(from) * 2))
 	tmap := make(map[[20]byte]int, (len(from)))
 
@@ -33,124 +27,122 @@ func Replace(w *bytes.Buffer, b []byte, from, to []Field) error {
 		tmap[h2] = i
 	}
 
-	for i := 0; i < len(b); i++ {
+	state := expectKey
-		switch {
+	ws, we := 0, len(b)
-		case ws == 0 && b[i] == '{' || b[i] == '[':
-			ws = i
 
+	s, e, d := 0, 0, 0
+	fi := -1
+
+	for i := 0; i < len(b); i++ {
+		// skip any left padding whitespace
+		if ws == 0 && (b[i] == '{' || b[i] == '[') {
+			ws = i
+		}
+
+		if state == expectObjClose || state == expectListClose {
+			switch b[i] {
+			case '{', '[':
+				d++
+			case '}', ']':
+				d--
+			}
+		}
+
+		switch {
 		case state == expectKey && b[i] == '"':
 			state = expectKeyClose
-			s = i + 1
+			s = i
-			continue
 
 		case state == expectKeyClose && b[i] == '"':
 			state = expectColon
-
+			h1 := sha1.Sum(b[(s + 1):i])
-		default:
+			if n, ok := fmap[h1]; ok {
-			continue
+				we = s
-		}
+				fi = n
-
-		if state != expectColon {
-			continue
-		}
-
-		h1 := sha1.Sum(b[s:i])
-		if n, ok := fmap[h1]; ok {
-			we = s
-			fi = n
-		}
-
-		e := 0
-		d := 0
-		for ; i < len(b); i++ {
-			if state == expectObjClose || state == expectListClose {
-				switch b[i] {
-				case '{', '[':
-					d++
-				case '}', ']':
-					d--
-				}
 			}
 
-			switch {
+		case state == expectColon && b[i] == ':':
-			case state == expectColon && b[i] == ':':
+			state = expectValue
-				state = expectValue
 
-			case state == expectValue && b[i] == '"':
+		case state == expectValue && b[i] == '"':
-				state = expectString
+			state = expectString
-				s = i
+			s = i
 
-			case state == expectString && b[i] == '"':
+		case state == expectString && b[i] == '"':
-				e = i
+			e = i
 
-			case state == expectValue && b[i] == '[':
+		case state == expectValue && b[i] == '[':
-				state = expectListClose
+			state = expectListClose
-				s = i
+			s = i
-				d++
+			d++
 
-			case state == expectListClose && d == 0 && b[i] == ']':
+		case state == expectListClose && d == 0 && b[i] == ']':
-				e = i
+			e = i
 
-			case state == expectValue && b[i] == '{':
+		case state == expectValue && b[i] == '{':
-				state = expectObjClose
+			state = expectObjClose
-				s = i
+			s = i
-				d++
+			d++
 
-			case state == expectObjClose && d == 0 && b[i] == '}':
+		case state == expectObjClose && d == 0 && b[i] == '}':
-				e = i
+			e = i
 
-			case state == expectValue && (b[i] >= '0' && b[i] <= '9'):
+		case state == expectValue && (b[i] >= '0' && b[i] <= '9'):
-				state = expectNumClose
+			state = expectNumClose
-				s = i
+			s = i
 
-			case state == expectNumClose &&
+		case state == expectNumClose &&
-				((b[i] < '0' || b[i] > '9') &&
+			((b[i] < '0' || b[i] > '9') &&
-					(b[i] != '.' && b[i] != 'e' && b[i] != 'E' && b[i] != '+' && b[i] != '-')):
+				(b[i] != '.' && b[i] != 'e' && b[i] != 'E' && b[i] != '+' && b[i] != '-')):
-				i--
+			i--
-				e = i
+			e = i
 
-			case state == expectValue &&
+		case state == expectValue &&
-				(b[i] == 'f' || b[i] == 'F' || b[i] == 't' || b[i] == 'T'):
+			(b[i] == 'f' || b[i] == 'F' || b[i] == 't' || b[i] == 'T'):
-				state = expectBoolClose
+			state = expectBoolClose
-				s = i
+			s = i
 
-			case state == expectBoolClose && (b[i] == 'e' || b[i] == 'E'):
+		case state == expectBoolClose && (b[i] == 'e' || b[i] == 'E'):
-				e = i
+			e = i
-			}
+		}
 
-			if e != 0 {
+		if e != 0 {
-				e++
+			e++
-				h2 := sha1.Sum(b[s:e])
 
-				if n, ok1 := fmap[h2]; ok1 && n == fi {
+			h2 := sha1.Sum(b[s:e])
-					ti, ok2 := tmap[h2]
+			replace := false
 
-					if ok2 {
+			if n, ok1 := fmap[h2]; ok1 && n == fi {
-						if _, err := w.Write(b[ws:we]); err != nil {
+				ti, ok2 := tmap[h2]
-							return err
+
-						}
+				if ok2 {
-						if _, err := w.Write(to[ti].Key); err != nil {
+					if _, err := w.Write(b[ws:(we + 1)]); err != nil {
-							return err
+						return err
-						}
-						if _, err := w.WriteString(`":`); err != nil {
-							return err
-						}
-						if _, err := w.Write(to[ti].Value); err != nil {
-							return err
-						}
-						ws = e
 					}
+					if _, err := w.Write(to[ti].Key); err != nil {
+						return err
+					}
+					if _, err := w.WriteString(`":`); err != nil {
+						return err
+					}
+					if _, err := w.Write(to[ti].Value); err != nil {
+						return err
+					}
+					replace = true
+					ws = e
 				}
-
-				if ws != e && (b[s] == '[' || b[s] == '{') {
-					i = s - 1
-				}
-
-				state = expectKey
-				we = len(b)
-				fi = -1
-				break
 			}
+
+			if !replace && (b[s] == '[' || b[s] == '{') {
+				// the i++ in the for loop will add 1 so we account for that (s - 1)
+				i = s - 1
+			}
+
+			state = expectKey
+			we = len(b)
+			fi = -1
+			e = 0
+			d = 0
 		}
 	}
 

json/strip.go

@@ -9,108 +9,96 @@ func Strip(b []byte, path []string) []byte {
 	state := expectKey
 
 	kb := make([][]byte, 0, len(path))
-	ki := 0
 	for _, k := range path {
 		kb = append(kb, []byte(k))
 	}
 
+	s, e, d := 0, 0, 0
+	ki := 0
+	pm := false
+
 	for i := 0; i < len(b); i++ {
+		if state == expectObjClose || state == expectListClose {
+			switch b[i] {
+			case '{', '[':
+				d++
+			case '}', ']':
+				d--
+			}
+		}
+
 		switch {
 		case state == expectKey && b[i] == '"':
 			state = expectKeyClose
-			s = i + 1
+			s = i
-			continue
 
 		case state == expectKeyClose && b[i] == '"':
 			state = expectColon
-		}
+			if ki == len(kb) {
-
+				ki = 0
-		if state != expectColon {
+			}
-			continue
+			pm = bytes.Equal(b[(s+1):i], kb[ki])
-		}
+			if pm {
-
+				ki++
-		if ki >= len(kb) {
-			return nil
-		}
-
-		if !bytes.Equal(b[s:i], kb[ki]) {
-			state = expectKey
-			continue
-		}
-
-		ki++
-
-		e := 0
-		d := 0
-		s := 0
-		for ; i < len(b); i++ {
-			if state == expectObjClose || state == expectListClose {
-				switch b[i] {
-				case '{', '[':
-					d++
-				case '}', ']':
-					d--
-				}
 			}
 
-			switch {
+		case state == expectColon && b[i] == ':':
-			case state == expectColon && b[i] == ':':
+			state = expectValue
-				state = expectValue
 
-			case state == expectValue && b[i] == '"':
+		case state == expectValue && b[i] == '"':
-				state = expectString
+			state = expectString
-				s = i
+			s = i
 
-			case state == expectString && b[i] == '"':
+		case state == expectString && b[i] == '"':
-				e = i
+			e = i
 
-			case state == expectValue && b[i] == '[':
+		case state == expectValue && b[i] == '[':
-				state = expectListClose
+			state = expectListClose
-				s = i
+			s = i
-				d++
+			d++
 
-			case state == expectListClose && d == 0 && b[i] == ']':
+		case state == expectListClose && d == 0 && b[i] == ']':
-				e = i
+			e = i
 
-			case state == expectValue && b[i] == '{':
+		case state == expectValue && b[i] == '{':
-				state = expectObjClose
+			state = expectObjClose
-				s = i
+			s = i
-				d++
+			d++
 
-			case state == expectObjClose && d == 0 && b[i] == '}':
+		case state == expectObjClose && d == 0 && b[i] == '}':
-				e = i
+			e = i
 
-			case state == expectValue && (b[i] >= '0' && b[i] <= '9'):
+		case state == expectValue && (b[i] >= '0' && b[i] <= '9'):
-				state = expectNumClose
+			state = expectNumClose
-				s = i
+			s = i
 
-			case state == expectNumClose &&
+		case state == expectNumClose &&
-				((b[i] < '0' || b[i] > '9') &&
+			((b[i] < '0' || b[i] > '9') &&
-					(b[i] != '.' && b[i] != 'e' && b[i] != 'E' && b[i] != '+' && b[i] != '-')):
+				(b[i] != '.' && b[i] != 'e' && b[i] != 'E' && b[i] != '+' && b[i] != '-')):
-				i--
+			i--
-				e = i
+			e = i
 
-			case state == expectValue &&
+		case state == expectValue &&
-				(b[i] == 'f' || b[i] == 'F' || b[i] == 't' || b[i] == 'T'):
+			(b[i] == 'f' || b[i] == 'F' || b[i] == 't' || b[i] == 'T'):
-				state = expectBoolClose
+			state = expectBoolClose
-				s = i
+			s = i
 
-			case state == expectBoolClose && (b[i] == 'e' || b[i] == 'E'):
+		case state == expectBoolClose && (b[i] == 'e' || b[i] == 'E'):
-				e = i
+			e = i
-			}
+		}
 
-			if e != 0 && (b[s] == '[' || b[s] == '{') {
+		if e != 0 {
-				e++
+			if pm && (b[s] == '[' || b[s] == '{') {
-				b = b[s:e]
+				b = b[s:(e + 1)]
 				i = 0
 
 				if ki == len(kb) {
 					return b
 				}
-
-				state = expectKey
-				break
 			}
+
+			state = expectKey
+			e = 0
 		}
 	}