From 7e79b01fda9469d4f52c748729df1e3fde864258 Mon Sep 17 00:00:00 2001
From: Peter Ohler <peter@ohler.com>
Date: Mon, 30 Oct 2023 19:23:09 -0400
Subject: [PATCH] Jp exists bug (#148)

* Fix jp exists bug
---
 CHANGELOG.md      |  4 ++++
 jp/parse.go       | 16 ++++++++++++----
 jp/parse_test.go  |  5 +++++
 jp/script_test.go |  4 ++++
 4 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index ad55c1b..b50eac5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,10 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 The structure and content of this file follows [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
+## [1.20.2] - 2023-10-30
+### Fixed
+- A script of `@.x` is now read correctly as `@.x exists true`.
+
 ## [1.20.1] - 2023-10-20
 ### Fixed
 - Calling jp.Set on a map or struct with a nil value no longer panics
diff --git a/jp/parse.go b/jp/parse.go
index a531b7a..2566e35 100644
--- a/jp/parse.go
+++ b/jp/parse.go
@@ -581,8 +581,12 @@ func (p *parser) readEquation() (eq *Equation) {
 		p.readFunc(search, eq)
 	default:
 		eq.left = p.readEqValue()
-		eq.o = p.readEqOp()
-		eq.right = p.readEqValue()
+		var right bool
+		if eq.o, right = p.readEqOp(); right {
+			eq.right = &Equation{result: true}
+		} else {
+			eq.right = p.readEqValue()
+		}
 	}
 	for p.pos < len(p.buf) {
 		b = p.nextNonSpace()
@@ -593,7 +597,7 @@ func (p *parser) readEquation() (eq *Equation) {
 		case ']':
 			return
 		}
-		o := p.readEqOp()
+		o, _ := p.readEqOp()
 		if eq.o.prec <= o.prec {
 			eq = &Equation{left: eq, o: o}
 			eq.right = p.readEqValue()
@@ -716,9 +720,13 @@ func partialOp(token []byte, b byte) bool {
 	return false
 }
 
-func (p *parser) readEqOp() (o *op) {
+func (p *parser) readEqOp() (o *op, right bool) {
 	var token []byte
 	b := p.nextNonSpace()
+	switch b {
+	case 0, ']', ')', '(':
+		return exists, true
+	}
 	for {
 		if eqMap[b] != 'o' {
 			if len(token) == 0 || !partialOp(token, b) {
diff --git a/jp/parse_test.go b/jp/parse_test.go
index 98ec09a..87e76b7 100644
--- a/jp/parse_test.go
+++ b/jp/parse_test.go
@@ -30,6 +30,9 @@ func TestParse(t *testing.T) {
 		{src: "@..", expect: "@.."},
 		{src: "@..x.y", expect: "@..x.y"},
 		{src: "@.*", expect: "@.*"},
+		{src: "@['x']", expect: "@.x"},
+		{src: "@['@x']", expect: "@['@x']"},
+		{src: "[?@['@type'] == 'something']", expect: "[?(@['@type'] == 'something')]"},
 		{src: "[1,2]", expect: "[1,2]"},
 		{src: "abc..def", expect: "abc..def"},
 		{src: "abc[*].def", expect: "abc[*].def"},
@@ -57,6 +60,8 @@ func TestParse(t *testing.T) {
 		{src: "$[ 1, 'a' , 2 ,'b' ]", expect: "$[1,'a',2,'b']"},
 		{src: "$[?(@.x == 'abc')]", expect: "$[?(@.x == 'abc')]"},
 		{src: "$[?(1==1)]", expect: "$[?(1 == 1)]"},
+		{src: "$[?(@.x)]", expect: "$[?(@.x exists true)]"},
+		{src: "$[?@.x]", expect: "$[?(@.x exists true)]"},
 		{src: `['a\\b']`, expect: `['a\\b']`},
 		{src: `[:]`, expect: `[:]`},
 		{src: `[::]`, expect: `[:]`},
diff --git a/jp/script_test.go b/jp/script_test.go
index 9a8cde4..1c198e5 100644
--- a/jp/script_test.go
+++ b/jp/script_test.go
@@ -61,6 +61,8 @@ func TestScriptParse(t *testing.T) {
 		{src: "(@.x<5)", expect: "(@.x < 5)"},
 		{src: "(@.x<123)", expect: "(@.x < 123)"},
 		{src: "(@.x == 3)", expect: "(@.x == 3)"},
+		{src: "(@['x'] == 3)", expect: "(@.x == 3)"},
+		{src: "(@['@x'] == 3)", expect: "(@['@x'] == 3)"},
 		{src: "(@.*.xyz==true)", expect: "(@.*.xyz == true)"},
 		{src: "(@.x.* == 3)", expect: "(@.x.* == 3)"},
 		{src: "(@.. == 3)", expect: "(@.. == 3)"},
@@ -83,6 +85,8 @@ func TestScriptParse(t *testing.T) {
 		{src: "(@ empty true)", expect: "(@ empty true)"},
 		{src: "(@ has true)", expect: "(@ has true)"},
 		{src: "(@ exists true)", expect: "(@ exists true)"},
+		{src: "(@)", expect: "(@ exists true)"},
+		{src: "@", expect: "(@ exists true)"},
 		{src: "(@ =~ /abc/)", expect: "(@ ~= /abc/)"},
 		{src: "(@ ~= /a\\/c/)", expect: "(@ ~= /a\\/c/)"},