Refactors fromString implementation (#107)

* prepare unit test for new implementation * adds new fromString implementation * fromString: handles Infinity * lint cleanup * improves doc * improves documentation
chrvadala · Feb 10, 2025 · 1179dd7 · 1179dd7
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diff --git a/docs/api.md b/docs/api.md
@@ -53,6 +53,10 @@ Any value could be a float or a string that contains a float</p>
 <dt><a href="#fromString">fromString(string)</a> ⇒ <code>Matrix</code></dt>
 <dd><p>Parse a string formatted as matrix(a,b,c,d,e,f)</p>
 </dd>
+<dt><del><a href="#fromStringLegacy">fromStringLegacy(string)</a> ⇒ <code>Matrix</code></del></dt>
+<dd><p>Parse a string formatted as matrix(a,b,c,d,e,f) - Legacy implementation of <code>fromString(matrix)</code>;
+Read this PR for details <a href="https://github.com/chrvadala/transformation-matrix/pull/107">https://github.com/chrvadala/transformation-matrix/pull/107</a></p>
+</dd>
 <dt><a href="#fromTransformAttribute">fromTransformAttribute(transformString)</a> ⇒ <code>Array.&lt;MatrixDescriptor&gt;</code></dt>
 <dd><p>Parser for SVG Trasform Attribute <a href="http://www.w3.org/TR/SVG/coords.html#TransformAttribute">http://www.w3.org/TR/SVG/coords.html#TransformAttribute</a></p>
 </dd>
@@ -287,6 +291,26 @@ Parse a string formatted as matrix(a,b,c,d,e,f)
 > fromString('matrix(1,2,3,4,5,6)')
 {a: 1, b: 2, c: 3, d: 4, c: 5, e: 6}
 ```
+<a name="fromStringLegacy"></a>
+
+## ~~fromStringLegacy(string) ⇒ <code>Matrix</code>~~
+***Deprecated***
+
+Parse a string formatted as matrix(a,b,c,d,e,f) - Legacy implementation of `fromString(matrix)`;
+Read this PR for details [https://github.com/chrvadala/transformation-matrix/pull/107](https://github.com/chrvadala/transformation-matrix/pull/107)
+
+**Kind**: global function  
+**Returns**: <code>Matrix</code> - Affine Matrix  
+
+| Param | Type | Description |
+| --- | --- | --- |
+| string | <code>string</code> | String with an affine matrix |
+
+**Example**  
+```js
+> fromStringLegacy('matrix(1,2,3,4,5,6)')
+{a: 1, b: 2, c: 3, d: 4, c: 5, e: 6}
+```
 <a name="fromTransformAttribute"></a>
 
 ## fromTransformAttribute(transformString) ⇒ <code>Array.&lt;MatrixDescriptor&gt;</code>

diff --git a/src/fromString.js b/src/fromString.js
@@ -14,6 +14,47 @@ const matrixRegex = /^matrix\(\s*([0-9_+-.e]+)\s*,\s*([0-9_+-.e]+)\s*,\s*([0-9_+
  * {a: 1, b: 2, c: 3, d: 4, c: 5, e: 6}
  */
 export function fromString (string) {
+  const parseFloatOrThrow = number => {
+    const n = parseFloat(number)
+    if (Number.isFinite(n)) return n // excludes NaN, +Infinite, -Infinite
+    throw new Error(`'${string}' is not a matrix`)
+  }
+
+  const prefix = string.substring(0, 7).toLowerCase()
+  const suffix = string.substring(string.length - 1)
+  const body = string.substring(7, string.length - 1)
+  const elements = body.split(',')
+
+  if (
+    prefix === 'matrix(' &&
+    suffix === ')' &&
+    elements.length === 6
+  ) {
+    return {
+      a: parseFloatOrThrow(elements[0]),
+      b: parseFloatOrThrow(elements[1]),
+      c: parseFloatOrThrow(elements[2]),
+      d: parseFloatOrThrow(elements[3]),
+      e: parseFloatOrThrow(elements[4]),
+      f: parseFloatOrThrow(elements[5])
+    }
+  }
+
+  throw new Error(`'${string}' is not a matrix`)
+}
+
+/**
+ * Parse a string formatted as matrix(a,b,c,d,e,f) - Legacy implementation of `fromString(matrix)`;
+ * Read this PR for details {@link https://github.com/chrvadala/transformation-matrix/pull/107}
+ * @param string {string} String with an affine matrix
+ * @deprecated
+ * @returns {Matrix} Affine Matrix
+ *
+ * @example
+ * > fromStringLegacy('matrix(1,2,3,4,5,6)')
+ * {a: 1, b: 2, c: 3, d: 4, c: 5, e: 6}
+ */
+export function fromStringLegacy (string) {
   const parsed = string.match(matrixRegex)
   if (parsed === null || parsed.length < 7) throw new Error(`'${string}' is not a matrix`)
   return {

diff --git a/test/fromString.spec.js b/test/fromString.spec.js
@@ -1,25 +1,55 @@
 /* global describe, it, expect */
-import { fromString } from '../src/fromString'
+import { fromString, fromStringLegacy } from '../src/fromString'
 
-describe('fromString', () => {
+describe.each([
+  ['fromString', fromString],
+  ['fromStringLegacy', fromStringLegacy]
+])('fromString (implementation: %s)', (fnName, fn) => {
   it('should parse a matrix from string', () => {
-    expect(fromString('matrix(1,2,3,4,5,6)')).toEqual({ a: 1, b: 2, c: 3, d: 4, e: 5, f: 6 })
-    expect(fromString('matrix(1 ,    2 , 3 , 4 , 5 , 6 )')).toEqual({ a: 1, b: 2, c: 3, d: 4, e: 5, f: 6 })
-    expect(fromString('MaTrIx(1,2,3,4,5,6)')).toEqual({ a: 1, b: 2, c: 3, d: 4, e: 5, f: 6 })
-    expect(fromString('matrix(1.1,2.2,3.3,4.4,5.5,6.6)')).toEqual({ a: 1.1, b: 2.2, c: 3.3, d: 4.4, e: 5.5, f: 6.6 })
-    expect(fromString('matrix(1.1 ,2.2  ,3.3 ,  4.4,  5.5,  6.6   )')).toEqual({ a: 1.1, b: 2.2, c: 3.3, d: 4.4, e: 5.5, f: 6.6 })
-    expect(fromString('matrix(1,2.2  ,3.3,4.4,5,  6   )')).toEqual({ a: 1, b: 2.2, c: 3.3, d: 4.4, e: 5, f: 6 })
+    expect(fn('matrix(1,2,3,4,5,6)')).toEqual({ a: 1, b: 2, c: 3, d: 4, e: 5, f: 6 })
+    expect(fn('matrix(1 ,    2 , 3 , 4 , 5 , 6 )')).toEqual({ a: 1, b: 2, c: 3, d: 4, e: 5, f: 6 })
+    expect(fn('MaTrIx(1,2,3,4,5,6)')).toEqual({ a: 1, b: 2, c: 3, d: 4, e: 5, f: 6 })
+    expect(fn('matrix(1.1,2.2,3.3,4.4,5.5,6.6)')).toEqual({ a: 1.1, b: 2.2, c: 3.3, d: 4.4, e: 5.5, f: 6.6 })
+    expect(fn('matrix(1.1 ,2.2  ,3.3 ,  4.4,  5.5,  6.6   )')).toEqual({ a: 1.1, b: 2.2, c: 3.3, d: 4.4, e: 5.5, f: 6.6 })
+    expect(fn('matrix(1,2.2  ,3.3,4.4,5,  6   )')).toEqual({ a: 1, b: 2.2, c: 3.3, d: 4.4, e: 5, f: 6 })
 
-    expect(fromString('matrix(-1.1,-2.2,-3.3,-4.4,-5.5,-6.6)')).toEqual({ a: -1.1, b: -2.2, c: -3.3, d: -4.4, e: -5.5, f: -6.6 })
-    expect(fromString('matrix(-1,-2,-3,-4,-5,-6)')).toEqual({ a: -1, b: -2, c: -3, d: -4, e: -5, f: -6 })
+    expect(fn('matrix(-1.1,-2.2,-3.3,-4.4,-5.5,-6.6)')).toEqual({ a: -1.1, b: -2.2, c: -3.3, d: -4.4, e: -5.5, f: -6.6 })
+    expect(fn('matrix(-1,-2,-3,-4,-5,-6)')).toEqual({ a: -1, b: -2, c: -3, d: -4, e: -5, f: -6 })
 
-    expect(fromString('matrix(+43e+21, -43e+21, +43e-21, -43e-21, 43e0, 0e0)')).toEqual({ a: +43e+21, b: -43e+21, c: +43e-21, d: -43e-21, e: 43, f: 0 })
+    expect(fn('matrix(+43e+21, -43e+21, +43e-21, -43e-21, 43e0, 0e0)')).toEqual({ a: +43e+21, b: -43e+21, c: +43e-21, d: -43e-21, e: 43, f: 0 })
 
-    expect(fromString.bind(this, 'matrix()')).toThrow()
-    expect(fromString.bind(this, 'matrix(1,2,3,4,5)')).toThrow()
-    expect(fromString.bind(this, 'matrix(a,b,c,d,e,f)')).toThrow()
+    expect(fn.bind(this, 'matrix()')).toThrow(new Error("'matrix()' is not a matrix"))
+    expect(fn.bind(this, 'matrix(1,2,3,4,5)')).toThrow(new Error("'matrix(1,2,3,4,5)' is not a matrix"))
+    expect(fn.bind(this, 'matrix(a,b,c,d,e,f)')).toThrow(new Error("'matrix(a,b,c,d,e,f)' is not a matrix"))
 
-    expect(fromString('matrix(6.123233995736766e-17,1,-1,6.123233995736766e-17,440,-350)'))
+    expect(fn.bind(this, 'matrix(Infinity,Infinity,Infinity,Infinity,Infinity,Infinity)'))
+      .toThrow(new Error("'matrix(Infinity,Infinity,Infinity,Infinity,Infinity,Infinity)' is not a matrix"))
+
+    expect(fn.bind(this, 'matrix(-Infinity,-Infinity,-Infinity,-Infinity,-Infinity,-Infinity)'))
+      .toThrow(new Error("'matrix(-Infinity,-Infinity,-Infinity,-Infinity,-Infinity,-Infinity)' is not a matrix"))
+
+    expect(fn('matrix(6.123233995736766e-17,1,-1,6.123233995736766e-17,440,-350)'))
       .toEqual({ a: 6.123233995736766e-17, b: 1, c: -1, d: 6.123233995736766e-17, e: 440, f: -350 })
+
+    if (fnName === 'fromString') {
+      // current version throws an exception in a case that number is NaN
+      expect(fn.bind(this, 'matrix(ee,ee,ee,ee,ee,ee)')).toThrow(new Error("'matrix(ee,ee,ee,ee,ee,ee)' is not a matrix"))
+      // current version ignores measures, supporting the ability to parse values like this 10px
+      expect(fn('matrix(1px,2px,3px,4px,5px,6px)')).toEqual({ a: 1, b: 2, c: 3, d: 4, e: 5, f: 6 })
+    }
+
+    if (fnName === 'fromStringLegacy') {
+      expect(fn('matrix(ee,ee,ee,ee,ee,ee)'))
+        .toEqual({
+          a: Number.NaN,
+          b: Number.NaN,
+          c: Number.NaN,
+          d: Number.NaN,
+          e: Number.NaN,
+          f: Number.NaN
+        })
+
+      expect(fn.bind(this, 'matrix(1px,2px,3px,4px,5px,6px)')).toThrow(new Error("'matrix(1px,2px,3px,4px,5px,6px)' is not a matrix"))
+    }
   })
 })