math: vector: Add read syntax.

* chickadee/math/vector.scm (read-vec): New procedure.  Extend reader.
* examples/lines.scm: Use new vector read syntax.
* examples/nine-patch.scm: Ditto.
* examples/sprite.scm: Ditto.
* examples/text.scm: Ditto.
* examples/tiled.scm: Ditto.

1 files changed, 26 insertions, 0 deletions

diff --git a/chickadee/math/vector.scm b/chickadee/math/vector.scm
index 78aa564..2ae9187 100644
--- a/chickadee/math/vector.scm
+++ b/chickadee/math/vector.scm
@@ -311,3 +311,29 @@ polar coordinate (R, THETA)."
         (set-vec3-x! v (- (vec3-x v) (vec3-x x)))
         (set-vec3-y! v (- (vec3-y v) (vec3-y x)))
         (set-vec3-z! v (- (vec3-z v) (vec3-z x))))))
+
+;; Reader macro for vectors.
+(define (read-vec chr port)
+  (define (consume-whitespace port)
+    (when (char-whitespace? (peek-char port))
+      (read-char port)
+      (consume-whitespace port)))
+  (if (eq? (peek-char port) #\()
+      (read-char port)
+      (error "expected opening #\\("))
+  (consume-whitespace port)
+  (let ((x (read port))
+        (y (read port)))
+    (if (eq? (peek-char port) #\))
+        (begin
+          (read-char port)
+          `(vec2 ,x ,y))
+        (let ((z (read port)))
+          (consume-whitespace port)
+          (if (eq? (peek-char port) #\))
+              (begin
+                (read-char port)
+                `(vec3 ,x ,y ,z))
+              (error "expected terminating #\\)"))))))
+
+(read-hash-extend #\v read-vec)