experimental support for wasm

Cargo.toml

@@ -10,6 +10,7 @@ repository = "https://github.com/connorskees/grass"
 authors = ["ConnorSkees <39542938+ConnorSkees@users.noreply.github.com>"]
 edition = "2018"
 exclude = ["*.scss", "sass-spec", "tests", "Cargo.lock"]
+default-run = "grass"
 
 [[bin]]
 name = "grass"
@@ -19,6 +20,7 @@ required-features = ["commandline"]
 [lib]
 name = "grass"
 path = "src/lib.rs"
+crate-type = ["cdylib", "rlib"]
 
 [dependencies]
 clap = { version = "2.33.0", optional = true }
@@ -29,6 +31,7 @@ once_cell = "1.3.1"
 rand = { version = "0.7.3", optional = true }
 codemap = "0.1.3"
 peekmore = "0.4.0"
+wasm-bindgen = { version = "0.2.60", optional = true }
 
 [features]
 default = ["commandline", "random"]
@@ -38,6 +41,8 @@ commandline = ["clap"]
 nightly = []
 # Option (enabled by default): enable the builtin functions `random([$limit])` and `unique-id()`
 random = ["rand"]
+# Option: compile to web assembly
+wasm = ["wasm-bindgen"]
 
 [dev-dependencies]
 tempfile = "3"

src/lib.rs

@@ -88,6 +88,9 @@ use codemap::{CodeMap, Span, Spanned};
 
 use peekmore::{PeekMore, PeekMoreIterator};
 
+#[cfg(feature = "wasm")]
+use wasm_bindgen::prelude::*;
+
 use crate::atrule::{eat_include, AtRule, AtRuleKind, Function, Mixin};
 pub use crate::error::{SassError, SassResult};
 use crate::imports::import;
@@ -124,6 +127,7 @@ mod utils;
 mod value;
 
 /// Represents a parsed SASS stylesheet with nesting
+#[cfg_attr(feature = "wasm", wasm_bindgen)]
 #[derive(Debug, Clone)]
 pub struct StyleSheet(Vec<Spanned<Stmt>>);
 
@@ -188,6 +192,28 @@ fn raw_to_parse_error(map: &CodeMap, err: SassError) -> SassError {
     SassError::from_loc(message, map.look_up_span(span))
 }
 
+#[cfg(feature = "wasm")]
+#[wasm_bindgen]
+impl StyleSheet {
+    pub fn new(input: String) -> Result<String, JsValue> {
+        let mut map = CodeMap::new();
+        let file = map.add_file("stdin".into(), input);
+        Ok(Css::from_stylesheet(StyleSheet(
+            StyleSheetParser {
+                lexer: Lexer::new(&file).peekmore(),
+                nesting: 0,
+                map: &map,
+            }
+            .parse_toplevel()
+            .map_err(|e| raw_to_parse_error(&map, e).to_string())?
+            .0,
+        ))
+        .map_err(|e| raw_to_parse_error(&map, e).to_string())?
+        .pretty_print()
+        .map_err(|e| raw_to_parse_error(&map, e).to_string())?)
+    }
+}
+
 impl StyleSheet {
     /// Write CSS to `buf`, constructed from a string
     ///
@@ -201,6 +227,7 @@ impl StyleSheet {
     /// }
     /// ```
     #[inline]
+    #[cfg(not(feature = "wasm"))]
     pub fn new(input: String) -> SassResult<String> {
         let mut map = CodeMap::new();
         let file = map.add_file("stdin".into(), input);
@@ -230,6 +257,7 @@ impl StyleSheet {
     /// }
     /// ```
     #[inline]
+    #[cfg(not(feature = "wasm"))]
     pub fn from_path<P: AsRef<Path> + Into<String> + Clone>(p: P) -> SassResult<String> {
         let mut map = CodeMap::new();
         let file = map.add_file(p.clone().into(), String::from_utf8(fs::read(p)?)?);