From be9510bc21724077fd27dcdb3825557475a6bb44 Mon Sep 17 00:00:00 2001
From: Nadrieril
Date: Sat, 21 Dec 2019 23:00:52 +0000
Subject: Generate parser manually to make the crate publishable

---
 Cargo.lock                      |  2 ++
 dhall/.gitignore                |  1 -
 dhall/Cargo.toml                |  2 ++
 dhall/build.rs                  | 28 ++++++++++++++++++++++++++--
 dhall/src/syntax/text/parser.rs | 12 +++++++++---
 5 files changed, 39 insertions(+), 6 deletions(-)
 delete mode 100644 dhall/.gitignore

diff --git a/Cargo.lock b/Cargo.lock
index ffdf17b..29aba92 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -80,7 +80,9 @@ dependencies = [
  "percent-encoding 2.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "pest 2.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "pest_consume 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "pest_generator 2.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "pretty_assertions 0.6.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.104 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_cbor 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "smallvec 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
diff --git a/dhall/.gitignore b/dhall/.gitignore
deleted file mode 100644
index 8a0bac6..0000000
--- a/dhall/.gitignore
+++ /dev/null
@@ -1 +0,0 @@
-src/dhall.pest
diff --git a/dhall/Cargo.toml b/dhall/Cargo.toml
index 44c8932..a9c237c 100644
--- a/dhall/Cargo.toml
+++ b/dhall/Cargo.toml
@@ -27,5 +27,7 @@ pretty_assertions = "0.6.1"
 [build-dependencies]
 walkdir = "2"
 abnf_to_pest = { version = "0.1.2", path = "../abnf_to_pest" }
+pest_generator = "2.1"
+quote = "1.0"
 
 
diff --git a/dhall/build.rs b/dhall/build.rs
index 50f423e..3021f03 100644
--- a/dhall/build.rs
+++ b/dhall/build.rs
@@ -408,9 +408,10 @@ fn generate_tests() -> std::io::Result<()> {
 }
 
 fn convert_abnf_to_pest() -> std::io::Result<()> {
+    let out_dir = env::var("OUT_DIR").unwrap();
     let abnf_path = "src/dhall.abnf";
     let visibility_path = "src/dhall.pest.visibility";
-    let pest_path = "src/dhall.pest";
+    let grammar_path = Path::new(&out_dir).join("dhall.pest");
     println!("cargo:rerun-if-changed={}", abnf_path);
     println!("cargo:rerun-if-changed={}", visibility_path);
 
@@ -427,7 +428,7 @@ fn convert_abnf_to_pest() -> std::io::Result<()> {
         }
     }
 
-    let mut file = File::create(pest_path)?;
+    let mut file = File::create(grammar_path)?;
     writeln!(&mut file, "// AUTO-GENERATED FILE. See build.rs.")?;
 
     // TODO: this is a cheat; properly support RFC3986 URLs instead
@@ -493,8 +494,31 @@ fn convert_abnf_to_pest() -> std::io::Result<()> {
     Ok(())
 }
 
+// Generate pest parser manually becaue otherwise we'd need to modify something outside of
+// OUT_DIR and that's forbidden by docs.rs.
+fn generate_pest_parser() -> std::io::Result<()> {
+    let out_dir = env::var("OUT_DIR").unwrap();
+    let grammar_path = Path::new(&out_dir).join("dhall.pest");
+    let grammar_path = grammar_path.to_str();
+    let output_path = Path::new(&out_dir).join("dhall_parser.rs");
+
+    let pest = quote::quote!(
+        #[grammar = #grammar_path]
+        struct DhallParser;
+    );
+    let derived = pest_generator::derive_parser(pest, false);
+    let file_contents = quote::quote!(
+        struct DhallParser;
+        #derived
+    );
+
+    let mut file = File::create(output_path)?;
+    writeln!(file, "{}", file_contents)
+}
+
 fn main() -> std::io::Result<()> {
     convert_abnf_to_pest()?;
+    generate_pest_parser()?;
     generate_tests()?;
     Ok(())
 }
diff --git a/dhall/src/syntax/text/parser.rs b/dhall/src/syntax/text/parser.rs
index 90cb4b1..832472b 100644
--- a/dhall/src/syntax/text/parser.rs
+++ b/dhall/src/syntax/text/parser.rs
@@ -156,9 +156,15 @@ lazy_static::lazy_static! {
     };
 }
 
-#[derive(Parser)]
-#[grammar = "dhall.pest"]
-struct DhallParser;
+// Generate pest parser manually becaue otherwise we'd need to modify something outside of OUT_DIR
+// and that's forbidden by docs.rs.
+// This is equivalent to:
+// ```
+// #[derive(Parser)
+// #[grammar = "..."]
+// struct DhallParser;
+// ```
+include!(concat!(env!("OUT_DIR"), "/dhall_parser.rs"));
 
 #[pest_consume::parser(parser = DhallParser, rule = Rule)]
 impl DhallParser {
-- 
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