From 38d33c2ea1c663139dd33cbf8b2a14b00c73af88 Mon Sep 17 00:00:00 2001
From: Steve Fan <29133953+stevefan1999-personal@users.noreply.github.com>
Date: Mon, 10 Apr 2023 21:39:20 +0800
Subject: [PATCH 1/8] add tracing support

---
 peg-macros/Cargo.toml   |  3 ++-
 peg-macros/translate.rs | 46 +++++++++++++++++++++++++++++++++--------
 peg-runtime/error.rs    |  1 +
 3 files changed, 40 insertions(+), 10 deletions(-)

diff --git a/peg-macros/Cargo.toml b/peg-macros/Cargo.toml
index c4a9e9d..1eaef25 100644
--- a/peg-macros/Cargo.toml
+++ b/peg-macros/Cargo.toml
@@ -11,9 +11,10 @@ edition = "2018"
 quote = "1.0"
 proc-macro2 = "1.0.24"
 peg-runtime = { version = "= 0.8.1", path = "../peg-runtime" }
+tracing = { version = "0.1.37", optional = true, features = ["attributes"] }
 
 [features]
-trace = []
+trace = ["dep:tracing"]
 
 [lib]
 proc-macro = true
diff --git a/peg-macros/translate.rs b/peg-macros/translate.rs
index 3afbe18..2bda766 100644
--- a/peg-macros/translate.rs
+++ b/peg-macros/translate.rs
@@ -168,8 +168,15 @@ fn make_parse_state(grammar: &Grammar) -> TokenStream {
         }
     }
 
+    let trace = if cfg!(feature = "trace") {
+        quote!( #[derive(Debug)] )
+    } else {
+        quote!()
+    };
+
     quote_spanned! { span =>
         #[allow(unused_parens)]
+        #trace
         struct ParseState<'input #(, #grammar_lifetime_params)*> {
             _phantom: ::core::marker::PhantomData<(&'input () #(, &#grammar_lifetime_params ())*)>,
             #(#cache_fields_def),*
@@ -232,18 +239,17 @@ fn compile_rule(context: &Context, rule: &Rule) -> TokenStream {
     let body = compile_expr(&context, &rule.expr, rule.ret_type.is_some());
 
     let wrapped_body = if cfg!(feature = "trace") {
-        let str_rule_name = rule.name.to_string();
         quote_spanned! { span => {
             let loc = ::peg::Parse::position_repr(__input, __pos);
-            println!("[PEG_TRACE] Attempting to match rule `{}` at {}", #str_rule_name, loc);
+            tracing::trace!(loc = %loc, "Attempting");
             let __peg_result: ::peg::RuleResult<#ret_ty> = {#body};
             match __peg_result {
                 ::peg::RuleResult::Matched(epos, _) => {
                     let eloc = ::peg::Parse::position_repr(__input, epos);
-                    println!("[PEG_TRACE] Matched rule `{}` at {} to {}", #str_rule_name, loc, eloc);
+                    tracing::trace!(eloc = %eloc, "Matched");
                 }
                 ::peg::RuleResult::Failed => {
-                    println!("[PEG_TRACE] Failed to match rule `{}` at {}", #str_rule_name, loc);
+                    tracing::trace!("Failed");
                 }
             }
 
@@ -261,12 +267,11 @@ fn compile_rule(context: &Context, rule: &Rule) -> TokenStream {
             let cache_field = format_ident!("{}_cache", rule.name);
 
             let cache_trace = if cfg!(feature = "trace") {
-                let str_rule_name = rule.name.to_string();
                 quote_spanned! { span =>
                     let loc = ::peg::Parse::position_repr(__input, __pos);
                     match &entry {
-                        &::peg::RuleResult::Matched(..) => println!("[PEG_TRACE] Cached match of rule {} at {}", #str_rule_name, loc),
-                        &Failed => println!("[PEG_TRACE] Cached fail of rule {} at {}", #str_rule_name, loc),
+                        &::peg::RuleResult::Matched(..) => tracing::trace!(loc = %loc, "Cache matched"),
+                        &::peg::RuleResult::Failed => tracing::trace!(loc = %loc, "Cache failed"),
                     };
                 }
             } else {
@@ -318,7 +323,16 @@ fn compile_rule(context: &Context, rule: &Rule) -> TokenStream {
         }
     };
 
+    let trace = if cfg!(feature = "trace") {
+        let str_rule_name = rule.name.to_string();
+
+        quote!( #[tracing::instrument(fields(rule = #str_rule_name))] )
+    } else {
+        quote!()
+    };
+
     quote_spanned! { span =>
+        #trace
         fn #name<'input #(, #grammar_lifetime_params)* #(, #ty_params)*>(__input: #input_ty, __state: #parse_state_ty, __err_state: &mut ::peg::error::ErrorState, __pos: usize #extra_args_def #(, #rule_params)*) -> ::peg::RuleResult<#ret_ty> {
             #![allow(non_snake_case, unused, clippy::redundant_closure_call)]
             #fn_body
@@ -363,11 +377,18 @@ fn compile_rule_export(context: &Context, rule: &Rule) -> TokenStream {
         quote_spanned! { span => ::peg::Parse::is_eof(__input, __pos) }
     };
 
+    let trace = if cfg!(feature = "trace") {
+        quote!( #[tracing::instrument] )
+    } else {
+        quote!()
+    };
+
     // Parse once. If it succeeds or throws an error, return that.
     // If it fails, parse again to determine the set of all tokens
     // that were expected at the failure position.
 
     quote_spanned! { span =>
+        #trace
         #doc
         #visibility fn #name<'input #(, #grammar_lifetime_params)* #(, #ty_params)*>(__input: #input_ty #extra_args_def #(, #rule_params)*) -> ::core::result::Result<#ret_ty, ::peg::error::ParseError<PositionRepr<#(#grammar_lifetime_params),*>>> {
             #![allow(non_snake_case, unused)]
@@ -921,17 +942,24 @@ fn compile_expr(context: &Context, e: &SpannedExpr, result_used: bool) -> TokenS
 
             let (enter, leave) = if cfg!(feature = "trace") {
                 (
-                    quote_spanned! {span => println!("[PEG_TRACE] Entering level {}", min_prec);},
-                    quote_spanned! {span => println!("[PEG_TRACE] Leaving level {}", min_prec);},
+                    quote_spanned! {span => tracing::trace!("Entering");},
+                    quote_spanned! {span => tracing::trace!("Leaving");},
                 )
             } else {
                 (quote!(), quote!())
             };
 
+            let trace = if cfg!(feature = "trace") {
+                quote!( #[tracing::instrument] )
+            } else {
+                quote!()
+            };
+
             // The closures below must be defined within the function call to which they are passed
             // due to https://github.com/rust-lang/rust/issues/41078
 
             quote_spanned! { span => {
+                #trace
                 fn __infix_parse<T, S>(
                     state: &mut S,
                     err_state: &mut ::peg::error::ErrorState,
diff --git a/peg-runtime/error.rs b/peg-runtime/error.rs
index b092643..18ac137 100644
--- a/peg-runtime/error.rs
+++ b/peg-runtime/error.rs
@@ -71,6 +71,7 @@ impl<L: Display + Debug> ::std::error::Error for ParseError<L> {
 }
 
 #[doc(hidden)]
+#[derive(Debug)]
 pub struct ErrorState {
     /// Furthest failure we've hit so far.
     pub max_err_pos: usize,

From 844ac41465fce348b88c283afba4faddc4be801e Mon Sep 17 00:00:00 2001
From: Steve Fan <29133953+stevefan1999-personal@users.noreply.github.com>
Date: Mon, 10 Apr 2023 22:19:48 +0800
Subject: [PATCH 2/8] update cargo lock

---
 Cargo.lock | 58 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 57 insertions(+), 1 deletion(-)

diff --git a/Cargo.lock b/Cargo.lock
index bbf5526..1636306 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -11,6 +11,12 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
 [[package]]
 name = "glob"
 version = "0.3.0"
@@ -45,12 +51,19 @@ dependencies = [
  "peg-runtime",
  "proc-macro2",
  "quote",
+ "tracing",
 ]
 
 [[package]]
 name = "peg-runtime"
 version = "0.8.1"
 
+[[package]]
+name = "pin-project-lite"
+version = "0.2.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e0a7ae3ac2f1173085d398531c705756c94a4c56843785df85a60c1a0afac116"
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.56"
@@ -89,7 +102,7 @@ checksum = "4c614d17805b093df4b147b51339e7e44bf05ef59fba1e45d83500bcfb4d8585"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.13",
 ]
 
 [[package]]
@@ -103,6 +116,17 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "syn"
+version = "1.0.109"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "72b64191b275b66ffe2469e8af2c1cfe3bafa67b529ead792a6d0160888b4237"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
 [[package]]
 name = "syn"
 version = "2.0.13"
@@ -123,6 +147,38 @@ dependencies = [
  "winapi-util",
 ]
 
+[[package]]
+name = "tracing"
+version = "0.1.37"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8ce8c33a8d48bd45d624a6e523445fd21ec13d3653cd51f681abf67418f54eb8"
+dependencies = [
+ "cfg-if",
+ "pin-project-lite",
+ "tracing-attributes",
+ "tracing-core",
+]
+
+[[package]]
+name = "tracing-attributes"
+version = "0.1.23"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4017f8f45139870ca7e672686113917c71c7a6e02d4924eda67186083c03081a"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 1.0.109",
+]
+
+[[package]]
+name = "tracing-core"
+version = "0.1.30"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "24eb03ba0eab1fd845050058ce5e616558e8f8d8fca633e6b163fe25c797213a"
+dependencies = [
+ "once_cell",
+]
+
 [[package]]
 name = "trybuild"
 version = "1.0.80"

From e0133807a0bb6b04adb9452cd1865f4ff2a3d9b6 Mon Sep 17 00:00:00 2001
From: Steve Fan <29133953+stevefan1999-personal@users.noreply.github.com>
Date: Mon, 10 Apr 2023 22:31:33 +0800
Subject: [PATCH 3/8] remove debug requirement for ParseState

---
 peg-macros/translate.rs | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/peg-macros/translate.rs b/peg-macros/translate.rs
index 2bda766..40b3327 100644
--- a/peg-macros/translate.rs
+++ b/peg-macros/translate.rs
@@ -168,15 +168,8 @@ fn make_parse_state(grammar: &Grammar) -> TokenStream {
         }
     }
 
-    let trace = if cfg!(feature = "trace") {
-        quote!( #[derive(Debug)] )
-    } else {
-        quote!()
-    };
-
     quote_spanned! { span =>
         #[allow(unused_parens)]
-        #trace
         struct ParseState<'input #(, #grammar_lifetime_params)*> {
             _phantom: ::core::marker::PhantomData<(&'input () #(, &#grammar_lifetime_params ())*)>,
             #(#cache_fields_def),*

From 13b3996e1870c01598b11316ba24e6e0be104bd2 Mon Sep 17 00:00:00 2001
From: Steve Fan <29133953+stevefan1999-personal@users.noreply.github.com>
Date: Mon, 10 Apr 2023 22:32:02 +0800
Subject: [PATCH 4/8] be conservative and pick only traces that are relevant

---
 peg-macros/translate.rs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/peg-macros/translate.rs b/peg-macros/translate.rs
index 40b3327..6a56d66 100644
--- a/peg-macros/translate.rs
+++ b/peg-macros/translate.rs
@@ -319,7 +319,7 @@ fn compile_rule(context: &Context, rule: &Rule) -> TokenStream {
     let trace = if cfg!(feature = "trace") {
         let str_rule_name = rule.name.to_string();
 
-        quote!( #[tracing::instrument(fields(rule = #str_rule_name))] )
+        quote!( #[tracing::instrument(skip_all, fields(rule = #str_rule_name, pos = __pos))] )
     } else {
         quote!()
     };
@@ -371,7 +371,7 @@ fn compile_rule_export(context: &Context, rule: &Rule) -> TokenStream {
     };
 
     let trace = if cfg!(feature = "trace") {
-        quote!( #[tracing::instrument] )
+        quote!( #[tracing::instrument(skip_all, err)] )
     } else {
         quote!()
     };
@@ -943,7 +943,7 @@ fn compile_expr(context: &Context, e: &SpannedExpr, result_used: bool) -> TokenS
             };
 
             let trace = if cfg!(feature = "trace") {
-                quote!( #[tracing::instrument] )
+                quote!( #[tracing::instrument(skip_all, fields(min_prec, lpos))] )
             } else {
                 quote!()
             };

From 7a9204885d1f91e6ca646a9c234767d6b50f32af Mon Sep 17 00:00:00 2001
From: Steve Fan <29133953+stevefan1999-personal@users.noreply.github.com>
Date: Mon, 10 Apr 2023 22:39:00 +0800
Subject: [PATCH 5/8] add tracing to dev dependencies

---
 Cargo.lock | 1 +
 Cargo.toml | 3 ++-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/Cargo.lock b/Cargo.lock
index 1636306..dca1f6e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -41,6 +41,7 @@ version = "0.8.1"
 dependencies = [
  "peg-macros",
  "peg-runtime",
+ "tracing",
  "trybuild",
 ]
 
diff --git a/Cargo.toml b/Cargo.toml
index 25302c4..e0070d5 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -19,6 +19,7 @@ peg-runtime = { path = "./peg-runtime", version = "= 0.8.1" }
 
 [dev-dependencies]
 trybuild = "1.0.80"
+tracing = "0.1.37"
 
 [[test]]
 name = "trybuild"
@@ -29,4 +30,4 @@ harness = false
 default = ["std"]
 trace = ["peg-macros/trace"]
 std = ["peg-runtime/std"]
-unstable = ["peg-runtime/unstable"]
\ No newline at end of file
+unstable = ["peg-runtime/unstable"]

From 6bc2559229e319923c8d06898905e5acd4753877 Mon Sep 17 00:00:00 2001
From: Steve Fan <29133953+stevefan1999-personal@users.noreply.github.com>
Date: Mon, 10 Apr 2023 22:48:18 +0800
Subject: [PATCH 6/8] add loc back to the span

---
 peg-macros/translate.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/peg-macros/translate.rs b/peg-macros/translate.rs
index 6a56d66..7f8560c 100644
--- a/peg-macros/translate.rs
+++ b/peg-macros/translate.rs
@@ -239,10 +239,10 @@ fn compile_rule(context: &Context, rule: &Rule) -> TokenStream {
             match __peg_result {
                 ::peg::RuleResult::Matched(epos, _) => {
                     let eloc = ::peg::Parse::position_repr(__input, epos);
-                    tracing::trace!(eloc = %eloc, "Matched");
+                    tracing::trace!(loc = %loc, eloc = %eloc, "Matched");
                 }
                 ::peg::RuleResult::Failed => {
-                    tracing::trace!("Failed");
+                    tracing::trace!(loc = %loc, "Failed");
                 }
             }
 

From 3db395abaea312e1d571faf99d33f35f6c619fcc Mon Sep 17 00:00:00 2001
From: Steve Fan <29133953+stevefan1999-personal@users.noreply.github.com>
Date: Mon, 10 Apr 2023 22:49:09 +0800
Subject: [PATCH 7/8] remove Debug from ErrorState

---
 peg-runtime/error.rs | 1 -
 1 file changed, 1 deletion(-)

diff --git a/peg-runtime/error.rs b/peg-runtime/error.rs
index 18ac137..b092643 100644
--- a/peg-runtime/error.rs
+++ b/peg-runtime/error.rs
@@ -71,7 +71,6 @@ impl<L: Display + Debug> ::std::error::Error for ParseError<L> {
 }
 
 #[doc(hidden)]
-#[derive(Debug)]
 pub struct ErrorState {
     /// Furthest failure we've hit so far.
     pub max_err_pos: usize,

From 9cfc49e7264885f59aed05635957e61bc166a879 Mon Sep 17 00:00:00 2001
From: Steve Fan <29133953+stevefan1999-personal@users.noreply.github.com>
Date: Tue, 11 Apr 2023 00:14:01 +0800
Subject: [PATCH 8/8] add a tracing test case

---
 Cargo.lock                | 111 ++++++++++++++++++++++++++++++++++++--
 Cargo.toml                |   2 +
 tests/run-pass/tracing.rs |  72 +++++++++++++++++++++++++
 3 files changed, 181 insertions(+), 4 deletions(-)
 create mode 100644 tests/run-pass/tracing.rs

diff --git a/Cargo.lock b/Cargo.lock
index dca1f6e..d34087b 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -25,9 +25,34 @@ checksum = "9b919933a397b79c37e33b77bb2aa3dc8eb6e165ad809e58ff75bc7db2e34574"
 
 [[package]]
 name = "itoa"
-version = "0.4.6"
+version = "1.0.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dc6f3ad7b9d11a0c00842ff8de1b60ee58661048eb8049ed33c73594f359d7e6"
+checksum = "453ad9f582a441959e5f0d088b02ce04cfe8d51a8eaf077f12ac6d3e94164ca6"
+
+[[package]]
+name = "lazy_static"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
+
+[[package]]
+name = "log"
+version = "0.4.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "abb12e687cfb44aa40f41fc3978ef76448f9b6038cad6aef4259d3c095a2382e"
+dependencies = [
+ "cfg-if",
+]
+
+[[package]]
+name = "nu-ansi-term"
+version = "0.46.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "77a8165726e8236064dbb45459242600304b42a5ea24ee2948e18e023bf7ba84"
+dependencies = [
+ "overload",
+ "winapi",
+]
 
 [[package]]
 name = "once_cell"
@@ -35,13 +60,21 @@ version = "1.17.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b7e5500299e16ebb147ae15a00a942af264cf3688f47923b8fc2cd5858f23ad3"
 
+[[package]]
+name = "overload"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b15813163c1d831bf4a13c3610c05c0d03b39feb07f7e09fa234dac9b15aaf39"
+
 [[package]]
 name = "peg"
 version = "0.8.1"
 dependencies = [
  "peg-macros",
  "peg-runtime",
+ "serde_json",
  "tracing",
+ "tracing-subscriber",
  "trybuild",
 ]
 
@@ -108,15 +141,30 @@ dependencies = [
 
 [[package]]
 name = "serde_json"
-version = "1.0.57"
+version = "1.0.95"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "164eacbdb13512ec2745fb09d51fd5b22b0d65ed294a1dcf7285a360c80a675c"
+checksum = "d721eca97ac802aa7777b701877c8004d950fc142651367300d21c1cc0194744"
 dependencies = [
  "itoa",
  "ryu",
  "serde",
 ]
 
+[[package]]
+name = "sharded-slab"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "900fba806f70c630b0a382d0d825e17a0f19fcd059a2ade1ff237bcddf446b31"
+dependencies = [
+ "lazy_static",
+]
+
+[[package]]
+name = "smallvec"
+version = "1.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a507befe795404456341dfab10cef66ead4c041f62b8b11bbb92bffe5d0953e0"
+
 [[package]]
 name = "syn"
 version = "1.0.109"
@@ -148,6 +196,16 @@ dependencies = [
  "winapi-util",
 ]
 
+[[package]]
+name = "thread_local"
+version = "1.1.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3fdd6f064ccff2d6567adcb3873ca630700f00b5ad3f060c25b5dcfd9a4ce152"
+dependencies = [
+ "cfg-if",
+ "once_cell",
+]
+
 [[package]]
 name = "tracing"
 version = "0.1.37"
@@ -178,6 +236,45 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "24eb03ba0eab1fd845050058ce5e616558e8f8d8fca633e6b163fe25c797213a"
 dependencies = [
  "once_cell",
+ "valuable",
+]
+
+[[package]]
+name = "tracing-log"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "78ddad33d2d10b1ed7eb9d1f518a5674713876e97e5bb9b7345a7984fbb4f922"
+dependencies = [
+ "lazy_static",
+ "log",
+ "tracing-core",
+]
+
+[[package]]
+name = "tracing-serde"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bc6b213177105856957181934e4920de57730fc69bf42c37ee5bb664d406d9e1"
+dependencies = [
+ "serde",
+ "tracing-core",
+]
+
+[[package]]
+name = "tracing-subscriber"
+version = "0.3.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a6176eae26dd70d0c919749377897b54a9276bd7061339665dd68777926b5a70"
+dependencies = [
+ "nu-ansi-term",
+ "serde",
+ "serde_json",
+ "sharded-slab",
+ "smallvec",
+ "thread_local",
+ "tracing-core",
+ "tracing-log",
+ "tracing-serde",
 ]
 
 [[package]]
@@ -201,6 +298,12 @@ version = "1.0.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e5464a87b239f13a63a501f2701565754bae92d243d4bb7eb12f6d57d2269bf4"
 
+[[package]]
+name = "valuable"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "830b7e5d4d90034032940e4ace0d9a9a057e7a45cd94e6c007832e39edb82f6d"
+
 [[package]]
 name = "winapi"
 version = "0.3.9"
diff --git a/Cargo.toml b/Cargo.toml
index e0070d5..9a883e6 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -20,6 +20,8 @@ peg-runtime = { path = "./peg-runtime", version = "= 0.8.1" }
 [dev-dependencies]
 trybuild = "1.0.80"
 tracing = "0.1.37"
+tracing-subscriber = { version = "0.3.16", features = ["json"] }
+serde_json = "1.0.95"
 
 [[test]]
 name = "trybuild"
diff --git a/tests/run-pass/tracing.rs b/tests/run-pass/tracing.rs
new file mode 100644
index 0000000..47e4547
--- /dev/null
+++ b/tests/run-pass/tracing.rs
@@ -0,0 +1,72 @@
+extern crate peg;
+
+peg::parser!(grammar parser() for str {
+    // JSON grammar (RFC 4627). Note that this only checks for valid JSON and does not build a syntax
+    // tree.
+
+    pub rule json() = _ (object() / array()) _
+
+    rule _() = [' ' | '\t' | '\r' | '\n']*
+    rule value_separator() = _ "," _
+
+    rule value()
+        = "false" / "true" / "null" / object() / array() / number() / string()
+
+    rule object()
+        = "{" _ member() ** value_separator() _ "}"
+
+    rule member()
+        = string() _ ":" _ value()
+
+    rule array()
+        = "[" _ (value() ** value_separator()) _ "]"
+
+    rule number()
+        = "-"? int() frac()? exp()? {}
+
+    rule int()
+        = ['0'] / ['1'..='9']['0'..='9']*
+
+    rule exp()
+        = ("e" / "E") ("-" / "+")? ['0'..='9']*<1,>
+
+    rule frac()
+        = "." ['0'..='9']*<1,>
+
+    // note: escaped chars not handled
+    rule string()
+        = "\"" (!"\"" [_])* "\""
+});
+
+fn main() {
+    #[cfg(feature = "trace")]
+    tracing_subscriber::fmt()
+        .with_max_level(tracing::Level::TRACE)
+        .json()
+        .init();
+
+    let input = r#"
+{
+	"X": 0.6e2,
+	"Y": 5,
+	"Z": -5.312344,
+	"Bool": false,
+	"Bool": true,
+	"Null": null,
+	"Attr": {
+		"Name": "bla",
+		"Siblings": [6, 1, 2, {}, {}, {}]
+	},
+	"Nested Array": [[[[[[[[[]]]]]]]]],
+	"Obj": {
+		"Child": {
+			"A": [],
+			"Child": {
+				"Child": {}
+			}
+		}
+	}
+}
+"#;
+    parser::json(input).unwrap();
+}