From 133f42ce2d99d6adb6b5885af6d20939dc4b6fe9 Mon Sep 17 00:00:00 2001
From: tidwall <joshbaker77@gmail.com>
Date: Tue, 1 Oct 2024 20:45:20 -0700
Subject: [PATCH] Generally faster parsing

This commit includes an optimization that increases overall
performance.

The gains are roughly between 20% to 300% depending on the size
of the JSON document. Larger documents will see the greates gains,
particularly when searching for keys that are deeply embedded, or
near the end of the document.
---
 README.md |   4 +-
 gjson.go  | 160 +++++++++++++++++++++++++++++++++++++++++++-----------
 2 files changed, 130 insertions(+), 34 deletions(-)

diff --git a/README.md b/README.md
index fc5dea5..387766d 100644
--- a/README.md
+++ b/README.md
@@ -438,7 +438,7 @@ Benchmarks of GJSON alongside [encoding/json](https://golang.org/pkg/encoding/js
 and [json-iterator](https://github.com/json-iterator/go)
 
 ```
-BenchmarkGJSONGet-10             14919366    240.9 ns/op      0 B/op     0 allocs/op
+BenchmarkGJSONGet-10             17893731    202.1 ns/op      0 B/op     0 allocs/op
 BenchmarkGJSONUnmarshalMap-10     1663548   2157 ns/op     1920 B/op    26 allocs/op
 BenchmarkJSONUnmarshalMap-10       832236   4279 ns/op     2920 B/op    68 allocs/op
 BenchmarkJSONUnmarshalStruct-10   1076475   3219 ns/op      920 B/op    12 allocs/op
@@ -489,6 +489,4 @@ widget.text.onMouseUp
 
 **
 
-Last run: Oct 1, 2024
-
 *These benchmarks were run on a MacBook Pro M1 Max using Go 1.22 and can be found [here](https://github.com/tidwall/gjson-benchmarks).*
diff --git a/gjson.go b/gjson.go
index 779fe61..5aa2a4f 100644
--- a/gjson.go
+++ b/gjson.go
@@ -1040,6 +1040,10 @@ func parseObjectPath(path string) (r objectPathResult) {
 	return
 }
 
+var vchars = [256]byte{
+	'"': 2, '{': 3, '(': 3, '[': 3, '}': 1, ')': 1, ']': 1,
+}
+
 func parseSquash(json string, i int) (int, string) {
 	// expects that the lead character is a '[' or '{' or '('
 	// squash the value, ignoring all nested arrays and objects.
@@ -1047,43 +1051,137 @@ func parseSquash(json string, i int) (int, string) {
 	s := i
 	i++
 	depth := 1
-	for ; i < len(json); i++ {
-		if json[i] >= '"' && json[i] <= '}' {
-			switch json[i] {
-			case '"':
+	var c byte
+	for i < len(json) {
+		for i < len(json)-8 {
+			jslice := json[i : i+8]
+			c = vchars[jslice[0]]
+			if c != 0 {
+				i += 0
+				goto token
+			}
+			c = vchars[jslice[1]]
+			if c != 0 {
+				i += 1
+				goto token
+			}
+			c = vchars[jslice[2]]
+			if c != 0 {
+				i += 2
+				goto token
+			}
+			c = vchars[jslice[3]]
+			if c != 0 {
+				i += 3
+				goto token
+			}
+			c = vchars[jslice[4]]
+			if c != 0 {
+				i += 4
+				goto token
+			}
+			c = vchars[jslice[5]]
+			if c != 0 {
+				i += 5
+				goto token
+			}
+			c = vchars[jslice[6]]
+			if c != 0 {
+				i += 6
+				goto token
+			}
+			c = vchars[jslice[7]]
+			if c != 0 {
+				i += 7
+				goto token
+			}
+			i += 8
+		}
+		c = vchars[json[i]]
+		if c == 0 {
+			i++
+			continue
+		}
+	token:
+		if c == 2 {
+			// '"' string
+			i++
+			s2 := i
+		nextquote:
+			for i < len(json)-8 {
+				jslice := json[i : i+8]
+				if jslice[0] == '"' {
+					i += 0
+					goto strchkesc
+				}
+				if jslice[1] == '"' {
+					i += 1
+					goto strchkesc
+				}
+				if jslice[2] == '"' {
+					i += 2
+					goto strchkesc
+				}
+				if jslice[3] == '"' {
+					i += 3
+					goto strchkesc
+				}
+				if jslice[4] == '"' {
+					i += 4
+					goto strchkesc
+				}
+				if jslice[5] == '"' {
+					i += 5
+					goto strchkesc
+				}
+				if jslice[6] == '"' {
+					i += 6
+					goto strchkesc
+				}
+				if jslice[7] == '"' {
+					i += 7
+					goto strchkesc
+				}
+				i += 8
+			}
+			goto strchkstd
+		strchkesc:
+			if json[i-1] != '\\' {
 				i++
-				s2 := i
-				for ; i < len(json); i++ {
-					if json[i] > '\\' {
-						continue
-					}
-					if json[i] == '"' {
-						// look for an escaped slash
-						if json[i-1] == '\\' {
-							n := 0
-							for j := i - 2; j > s2-1; j-- {
-								if json[j] != '\\' {
-									break
-								}
-								n++
-							}
-							if n%2 == 0 {
-								continue
-							}
+				continue
+			}
+		strchkstd:
+			for i < len(json) {
+				if json[i] > '\\' || json[i] != '"' {
+					i++
+					continue
+				}
+				// look for an escaped slash
+				if json[i-1] == '\\' {
+					n := 0
+					for j := i - 2; j > s2-1; j-- {
+						if json[j] != '\\' {
+							break
 						}
-						break
+						n++
+					}
+					if n%2 == 0 {
+						i++
+						goto nextquote
 					}
 				}
-			case '{', '[', '(':
-				depth++
-			case '}', ']', ')':
-				depth--
-				if depth == 0 {
-					i++
-					return i, json[s:i]
-				}
+				break
+			}
+		} else {
+			// '{', '[', '(', '}', ']', ')'
+			// open close tokens
+			depth += int(c) - 2
+			if depth == 0 {
+				i++
+				return i, json[s:i]
 			}
 		}
+		i++
 	}
 	return i, json[s:]
 }