Adds file_exists function (#43)

* Adds file_exists

* Updates the README

README.md

@@ -93,7 +93,7 @@ The default features are:
 
 Additional features are:
 * url: Faster replacements for `url_encode` and `url_decode`.
-* file: Faster replacements for `file2text` and `text2file`.
+* file: Faster replacements for `file2text` and `text2file`, as well as reading or checking if files exist.
 * hash: Faster replacement for `md5`, support for SHA-1, SHA-256, and SHA-512. Requires OpenSSL on Linux.
 
 ## Installing

build.rs

@@ -82,6 +82,7 @@ fn main() {
             f,
             r#"
 #define rustg_file_read(fname) call(RUST_G, "file_read")(fname)
+#define rustg_file_exists(fname) call(RUST_G, "file_exists")(fname)
 #define rustg_file_write(text, fname) call(RUST_G, "file_write")(text, fname)
 #define rustg_file_append(text, fname) call(RUST_G, "file_append")(text, fname)
 

src/file.rs

@@ -8,6 +8,10 @@ byond_fn! { file_read(path) {
     read(path).ok()
 } }
 
+byond_fn! { file_exists(path) {
+    Some(exists(path))
+} }
+
 byond_fn! { file_write(data, path) {
     write(data, path).err()
 } }
@@ -27,6 +31,11 @@ fn read(path: &str) -> Result<String> {
     Ok(content)
 }
 
+fn exists(path: &str) -> String {
+    let path = std::path::Path::new(path);
+    path.exists().to_string()
+}
+
 fn write(data: &str, path: &str) -> Result<usize> {
     let path: &std::path::Path = path.as_ref();
     if let Some(parent) = path.parent() {