From 91d4ac3ac097ea89bf275120cfa4ca37d2d6190d Mon Sep 17 00:00:00 2001
From: Kacper Madej <kacperoza@gmail.com>
Date: Fri, 10 Jan 2025 12:14:57 +0700
Subject: [PATCH] Fix expression chaining

---
 core/json/mod.rs       | 4 ++++
 core/translate/expr.rs | 5 +++--
 testing/json.test      | 4 ++++
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/core/json/mod.rs b/core/json/mod.rs
index 59adc4bb2..f0a362ab6 100644
--- a/core/json/mod.rs
+++ b/core/json/mod.rs
@@ -290,6 +290,10 @@ pub fn json_type(value: &OwnedValue, path: Option<&OwnedValue>) -> crate::Result
 
 /// Returns the value at the given JSON path. If the path does not exist, it returns None.
 /// If the path is an invalid path, returns an error.
+///
+/// *strict* - if false, we will try to resolve the path even if it does not start with "$"
+///   in a way that's compatible with the `->` and `->>` operators. See examples in the docs:
+///   https://sqlite.org/json1.html#the_and_operators
 fn json_extract_single<'a>(
     json: &'a Val,
     path: &OwnedValue,
diff --git a/core/translate/expr.rs b/core/translate/expr.rs
index 6897308c0..f3834601e 100644
--- a/core/translate/expr.rs
+++ b/core/translate/expr.rs
@@ -457,9 +457,10 @@ pub fn translate_expr(
     match expr {
         ast::Expr::Between { .. } => todo!(),
         ast::Expr::Binary(e1, op, e2) => {
-            let e1_reg = program.alloc_register();
+            let e1_reg = program.alloc_registers(2);
+            let e2_reg = e1_reg + 1;
+
             translate_expr(program, referenced_tables, e1, e1_reg, resolver)?;
-            let e2_reg = program.alloc_register();
             translate_expr(program, referenced_tables, e2, e2_reg, resolver)?;
 
             match op {
diff --git a/testing/json.test b/testing/json.test
index 7d0d93203..f8472db96 100755
--- a/testing/json.test
+++ b/testing/json.test
@@ -331,6 +331,10 @@ do_execsql_test json_arrow_shift_implicit_real_cast {
 #  SELECT '[1,2,3]' ->> false
 #} {{1}}
 
+do_execsql_test json_arrow_chained {
+  select '{"a":2,"c":[4,5,{"f":7}]}' -> 'c' -> 2 ->> 'f'
+} {{7}}
+
 # TODO: fix me - this passes on SQLite and needs to be fixed in Limbo.
 do_execsql_test json_extract_multiple_null_paths {
     SELECT json_extract(1, null, null, null)