use OUT_DIR env variable if defined as prefix path for location of te…

…mporary bindings.json file. fixes #72 (#82)

cli.ts

@@ -2,6 +2,7 @@
 
 import { ensureDir } from "https://deno.land/[email protected]/fs/ensure_dir.ts";
 import { parse } from "https://deno.land/[email protected]/flags/mod.ts";
+import { join } from "https://deno.land/[email protected]/path/mod.ts";
 import { codegen } from "./codegen.ts";
 
 const flags = parse(Deno.args, { "--": true });
@@ -11,6 +12,8 @@ const fetchPrefix = typeof flags.release == "string"
   ? flags.release
   : "../target/" + (release ? "release" : "debug");
 
+const metafile = join(Deno.env.get("OUT_DIR") || "", "bindings.json");
+
 async function build() {
   const cmd = ["cargo", "build"];
   if (release) cmd.push("--release");
@@ -23,7 +26,7 @@ let source = null;
 async function generate() {
   let conf;
   try {
-    conf = JSON.parse(await Deno.readTextFile("bindings.json"));
+    conf = JSON.parse(await Deno.readTextFile(metafile));
   } catch (_) {
     // Nothing to update.
     return;
@@ -44,16 +47,16 @@ async function generate() {
     },
   );
 
-  await Deno.remove("bindings.json");
+  await Deno.remove(metafile);
 }
 
 try {
-  await Deno.remove("bindings.json");
+  await Deno.remove(metafile);
 } catch (e) {
   // no op
 }
 
-const status = await build().catch((_) => Deno.removeSync("bindings.json"));
+const status = await build().catch((_) => Deno.removeSync(metafile));
 if (status?.success || typeof flags.release == "string") {
   await generate();
   if (source) {

deno_bindgen_macro/src/lib.rs

@@ -7,6 +7,7 @@ use std::env;
 use std::fs::OpenOptions;
 use std::io::Read;
 use std::io::Write;
+use std::path::Path;
 use syn::parse_macro_input;
 use syn::parse_quote;
 use syn::ItemFn;
@@ -22,8 +23,6 @@ use crate::derive_struct::process_struct;
 use crate::meta::Glue;
 use crate::meta::Type;
 
-const METAFILE: &str = "bindings.json";
-
 #[cfg(target_endian = "little")]
 const ENDIANNESS: bool = true;
 
@@ -32,7 +31,13 @@ const ENDIANNESS: bool = false;
 
 #[proc_macro_attribute]
 pub fn deno_bindgen(attr: TokenStream, input: TokenStream) -> TokenStream {
-  let mut metadata: Glue = match OpenOptions::new().read(true).open(METAFILE) {
+
+  let metafile_path: String = match env::var("OUT_DIR") {
+    Ok(out_dir) => Path::new(&out_dir).join("bindings.json").into_os_string().into_string().unwrap(),
+    Err(_e) => String::from("bindings.json")
+  };
+
+  let mut metadata: Glue = match OpenOptions::new().read(true).open(metafile_path.as_str()) {
     Ok(mut fd) => {
       let mut meta = String::new();
       fd.read_to_string(&mut meta)
@@ -50,7 +55,7 @@ pub fn deno_bindgen(attr: TokenStream, input: TokenStream) -> TokenStream {
   let mut metafile = OpenOptions::new()
     .write(true)
     .create(true)
-    .open(METAFILE)
+    .open(metafile_path.as_str())
     .expect("Error opening meta file");
 
   match syn::parse::<ItemFn>(input.clone()) {