[librsvg: 22/25] stroke-dash-array: Use lazy_static to cache the regex query.

[Federico Mena Quintero <federico src gnome org>]

commit 156c2aa758657f746de8705d836763bfbe8750fc
Author: Jordan Petridis <jordanpetridis protonmail com>
Date:   Thu Feb 1 22:21:32 2018 +0200

    stroke-dash-array: Use lazy_static to cache the regex query.

 rust/Cargo.lock    |  1 +
 rust/Cargo.toml    |  1 +
 rust/src/length.rs | 12 ++++++++----
 rust/src/lib.rs    |  3 +++
 4 files changed, 13 insertions(+), 4 deletions(-)
---
diff --git a/rust/Cargo.lock b/rust/Cargo.lock
index 68faf02..779a004 100644
--- a/rust/Cargo.lock
+++ b/rust/Cargo.lock
@@ -283,6 +283,7 @@ dependencies = [
  "glib 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "glib-sys 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "itertools 0.7.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.36 (registry+https://github.com/rust-lang/crates.io-index)",
  "pango 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "pango-sys 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
diff --git a/rust/Cargo.toml b/rust/Cargo.toml
index 8e2b450..487e91d 100644
--- a/rust/Cargo.toml
+++ b/rust/Cargo.toml
@@ -11,6 +11,7 @@ itertools = "0.7.4"
 pango = "0.3.0"
 pango-sys = "0.5.0"
 cssparser = "0.23"
+lazy_static = "1.0.0"
 
 [dependencies.cairo-sys-rs]
 version = "0.5.0"
diff --git a/rust/src/length.rs b/rust/src/length.rs
index d091aa6..0cf1b0e 100644
--- a/rust/src/length.rs
+++ b/rust/src/length.rs
@@ -330,6 +330,11 @@ fn parse_stroke_dash_array(s: &str) -> Result<StrokeDasharray, AttributeError> {
 
 // This does not handle "inherit" or "none" state, the caller is responsible for that.
 fn parse_dash_array(s: &str) -> Result<Vec<RsvgLength>, AttributeError> {
+    lazy_static!{
+        // The unwrap here is fine AS LONG the regex query is valid.
+        static ref COMMAS: Regex = Regex::new(r",\s*,").unwrap();
+    };
+
     let s = s.trim();
 
     if s.is_empty() {
@@ -343,10 +348,8 @@ fn parse_dash_array(s: &str) -> Result<Vec<RsvgLength>, AttributeError> {
         }
     }
 
-    // TODO: Use lazy static to avoid constructing the regex on each function call.
-    let commas = Regex::new(r",\s*,").unwrap();
-
-    if commas.is_match(s) {
+    // Commas must be followed by a value.
+    if COMMAS.is_match(s) {
         return Err(AttributeError::Parse(ParseError::new("expected number, found comma")));
     }
 
@@ -598,6 +601,7 @@ mod tests {
         assert_eq!(parse_dash_array(""), Err(AttributeError::Parse(ParseError::new("empty string"))));
         assert_eq!(parse_dash_array("\t  \n     "), Err(AttributeError::Parse(ParseError::new("empty 
string"))));
         assert!(parse_dash_array(",,,").is_err());
+        assert!(parse_dash_array("10,  \t, 20 \n").is_err());
         // No trailling commas allowed, parse error
         assert!(parse_dash_array("10,").is_err());
         // A comma should be followed by a number
diff --git a/rust/src/lib.rs b/rust/src/lib.rs
index 4823049..453dac8 100644
--- a/rust/src/lib.rs
+++ b/rust/src/lib.rs
@@ -13,6 +13,9 @@ extern crate pango;
 extern crate pango_sys;
 extern crate regex;
 
+#[macro_use]
+extern crate lazy_static;
+
 #[macro_use]
 extern crate downcast_rs;