Replace catch-all experimental flag with fine-grained boolean preferences initialized from a JSON document.

3 files changed, 53 insertions, 24 deletions

diff --git a/components/util/lib.rs b/components/util/lib.rs
index 4c2ef7f6746..b10d5b2a2d1 100644
--- a/components/util/lib.rs
+++ b/components/util/lib.rs
@@ -60,6 +60,7 @@ pub mod logical_geometry;
 pub mod mem;
 pub mod opts;
 pub mod persistent_list;
+pub mod prefs;
 pub mod range;
 pub mod resource_files;
 pub mod str;
diff --git a/components/util/opts.rs b/components/util/opts.rs
index af8c629fcdc..7c42d60380e 100644
--- a/components/util/opts.rs
+++ b/components/util/opts.rs
@@ -17,7 +17,6 @@ use std::fs::{File, PathExt};
 use std::io::{self, Read, Write};
 use std::path::Path;
 use std::process;
-use std::sync::atomic::{AtomicBool, Ordering, ATOMIC_BOOL_INIT};
 use url::{self, Url};
 
 /// Global flags for Servo, currently set on the command line.
@@ -50,9 +49,6 @@ pub struct Opts {
     /// and cause it to produce output on that interval (`-m`).
     pub mem_profiler_period: Option<f64>,
 
-    /// Enable experimental web features (`-e`).
-    pub enable_experimental: bool,
-
     /// The number of threads to use for layout (`-y`). Defaults to 1, which results in a recursive
     /// sequential algorithm.
     pub layout_threads: usize,
@@ -384,7 +380,6 @@ pub fn default_opts() -> Opts {
         device_pixels_per_px: None,
         time_profiler_period: None,
         mem_profiler_period: None,
-        enable_experimental: false,
         layout_threads: 1,
         nonincremental_layout: false,
         nossl: false,
@@ -434,7 +429,6 @@ pub fn from_cmdline_args(args: &[String]) {
     opts.optopt("o", "output", "Output file", "output.png");
     opts.optopt("s", "size", "Size of tiles", "512");
     opts.optopt("", "device-pixel-ratio", "Device pixels per px", "");
-    opts.optflag("e", "experimental", "Enable experimental web features");
     opts.optopt("t", "threads", "Number of paint threads", "1");
     opts.optflagopt("p", "profile", "Profiler flag and output interval", "10");
     opts.optflagopt("m", "memory-profile", "Memory profiler flag and output interval", "10");
@@ -589,7 +583,6 @@ pub fn from_cmdline_args(args: &[String]) {
         device_pixels_per_px: device_pixels_per_px,
         time_profiler_period: time_profiler_period,
         mem_profiler_period: mem_profiler_period,
-        enable_experimental: opt_match.opt_present("e"),
         layout_threads: layout_threads,
         nonincremental_layout: nonincremental_layout,
         nossl: nossl,
@@ -632,19 +625,6 @@ pub fn from_cmdline_args(args: &[String]) {
     set_defaults(opts);
 }
 
-static EXPERIMENTAL_ENABLED: AtomicBool = ATOMIC_BOOL_INIT;
-
-/// Turn on experimental features globally. Normally this is done
-/// during initialization by `set` or `from_cmdline_args`, but
-/// tests that require experimental features will also set it.
-pub fn set_experimental_enabled(new_value: bool) {
-    EXPERIMENTAL_ENABLED.store(new_value, Ordering::SeqCst);
-}
-
-pub fn experimental_enabled() -> bool {
-    EXPERIMENTAL_ENABLED.load(Ordering::SeqCst)
-}
-
 // Make Opts available globally. This saves having to clone and pass
 // opts everywhere it is used, which gets particularly cumbersome
 // when passing through the DOM structures.
@@ -653,7 +633,7 @@ const INVALID_OPTIONS: *mut Opts = 0x01 as *mut Opts;
 
 lazy_static! {
     static ref OPTIONS: Opts = {
-        let opts = unsafe {
+        unsafe {
             let initial = if !DEFAULT_OPTIONS.is_null() {
                 let opts = Box::from_raw(DEFAULT_OPTIONS);
                 *opts
@@ -662,9 +642,7 @@ lazy_static! {
             };
             DEFAULT_OPTIONS = INVALID_OPTIONS;
             initial
-        };
-        set_experimental_enabled(opts.enable_experimental);
-        opts
+        }
     };
 }
 
diff --git a/components/util/prefs.rs b/components/util/prefs.rs
new file mode 100644
index 00000000000..8c38b6b8152
--- /dev/null
+++ b/components/util/prefs.rs
@@ -0,0 +1,50 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use resource_files::resources_dir_path;
+use rustc_serialize::json::Json;
+use std::collections::HashMap;
+use std::fs::File;
+use std::sync::{Arc, Mutex};
+
+lazy_static! {
+    static ref PREFS: Arc<Mutex<HashMap<String, bool>>> = {
+        let prefs = read_prefs().unwrap_or(HashMap::new());
+        Arc::new(Mutex::new(prefs))
+    };
+}
+
+fn read_prefs() -> Result<HashMap<String, bool>, ()> {
+    let mut path = resources_dir_path();
+    path.push("prefs.json");
+
+    let mut file = try!(File::open(path).or_else(|e| {
+        println!("Error opening preferences: {:?}.", e);
+        Err(())
+    }));
+    let json = try!(Json::from_reader(&mut file).or_else(|e| {
+        println!("Ignoring invalid JSON in preferences: {:?}.", e);
+        Err(())
+    }));
+
+    let mut prefs = HashMap::new();
+    if let Some(obj) = json.as_object() {
+        for (name, value) in obj.iter() {
+            if let Some(bool_value) = value.as_boolean() {
+                prefs.insert(name.clone(), bool_value);
+            } else {
+                println!("Ignoring non-boolean preference value for {:?}", name);
+            }
+        }
+    }
+    Ok(prefs)
+}
+
+pub fn get_pref(name: &str, default: bool) -> bool {
+    *PREFS.lock().unwrap().get(name).unwrap_or(&default)
+}
+
+pub fn set_pref(name: String, value: bool) {
+    let _ = PREFS.lock().unwrap().insert(name, value);
+}