[librsvg] parse_transform.lalrpop: Parse chained transform lists

[Federico Mena Quintero <federico src gnome org>]

commit 03138e684e09130747293a0e7a2946a2c311000c
Author: Federico Mena Quintero <federico gnome org>
Date:   Wed Mar 22 09:20:45 2017 -0600

    parse_transform.lalrpop: Parse chained transform lists

 rust/src/parse_transform.lalrpop |   27 +++++++++++++++++++++------
 rust/src/parsers.rs              |   17 +++++++++++++++++
 2 files changed, 38 insertions(+), 6 deletions(-)
---
diff --git a/rust/src/parse_transform.lalrpop b/rust/src/parse_transform.lalrpop
index 9da4537..a99df98 100644
--- a/rust/src/parse_transform.lalrpop
+++ b/rust/src/parse_transform.lalrpop
@@ -12,13 +12,28 @@ use pt::cairo::MatrixTrait;
 
 grammar;
 
-pub Transform: cairo::Matrix = {
+pub TransformList: cairo::Matrix = {
+    // Note that the grammar in https://www.w3.org/TR/SVG/coords.html#TransformAttribute
+    // has this:
+    //
+    //   transforms:
+    //     transform
+    //     | transform comma-wsp+ transforms
+    //
+    // I think the "comma-wsp+" should really be "comma-wsp" as in the
+    // rest of the SVG grammar.  Here we will use our usual "comma?" and
+    // hope that the SVG test suite catches errors in our grammar.
+    <a: TransformList> comma? <b: Transform> => cairo::Matrix::multiply (&b, &a),
+    Transform
+};
+
+Transform: cairo::Matrix = {
     Matrix,
-//    Translate,
-//    Scale,
-//    Rotate,
-//    SkewX,
-//    SkewY
+    Translate,
+    Scale,
+    Rotate,
+    SkewX,
+    SkewY
 };
 
 pub Matrix: cairo::Matrix = "matrix" "(" <Num> comma? <Num> comma? <Num> comma? <Num> comma? <Num> comma? 
<Num> ")" =>
diff --git a/rust/src/parsers.rs b/rust/src/parsers.rs
index 09b47fd..9675db3 100644
--- a/rust/src/parsers.rs
+++ b/rust/src/parsers.rs
@@ -372,4 +372,21 @@ mod parse_transform_tests {
     fn parses_skew_y () {
         assert_eq! (parse_SkewY ("skewY (30)").unwrap (), make_skew_y_matrix (30.0));
     }
+
+    #[test]
+    fn parses_transform_list () {
+        let t = cairo::Matrix::new (1.0, 0.0, 0.0, 1.0, 20.0, 30.0);
+        let s = cairo::Matrix::new (10.0, 0.0, 0.0, 10.0, 0.0, 0.0);
+        let r = make_rotation_matrix (30.0, 10.0, 10.0);
+
+        assert_eq! (parse_TransformList ("scale(10)rotate(30, 10, 10)").unwrap (),
+                    cairo::Matrix::multiply (&r, &s));
+
+        assert_eq! (parse_TransformList ("translate(20, 30), scale (10)").unwrap (),
+                    cairo::Matrix::multiply (&s, &t));
+
+        let a = cairo::Matrix::multiply (&s, &t);
+        assert_eq! (parse_TransformList ("translate(20, 30), scale (10) rotate (30 10 10)").unwrap (),
+                    cairo::Matrix::multiply (&r, &a));
+    }
 }