From bb3328d5b54d7215d5f192a2e0925258dbb860b2 Mon Sep 17 00:00:00 2001
From: Bogdan Chadkin <trysound@yandex.ru>
Date: Fri, 26 Feb 2021 18:06:03 +0300
Subject: [PATCH 01/12] Implement new path parser

Regexps are quite leaky for complex parsing. Regression tests caught
a few issues related to path parser.

In this diff I implemented the new spec-compliant parser which solves
2 regression cases and covers many edge cases hard to handle with
regexps.
---
 lib/path.js      | 199 +++++++++++++++++++++++++++++++++++++++++++++++
 plugins/_path.js |  99 +++++------------------
 2 files changed, 217 insertions(+), 81 deletions(-)
 create mode 100644 lib/path.js

diff --git a/lib/path.js b/lib/path.js
new file mode 100644
index 000000000..689cac68d
--- /dev/null
+++ b/lib/path.js
@@ -0,0 +1,199 @@
+'use strict';
+
+// Based on https://www.w3.org/TR/SVG11/paths.html#PathDataBNF
+
+const argsCountPerCommand = {
+  M: 2,
+  m: 2,
+  Z: 0,
+  z: 0,
+  L: 2,
+  l: 2,
+  H: 1,
+  h: 1,
+  V: 1,
+  v: 1,
+  C: 6,
+  c: 6,
+  S: 4,
+  s: 4,
+  Q: 4,
+  q: 4,
+  T: 2,
+  t: 2,
+  A: 7,
+  a: 7
+};
+
+const isCommand = c => {
+  return c in argsCountPerCommand;
+};
+
+const isWsp = c => {
+  const codePoint = c.codePointAt(0);
+  return (
+    codePoint === 0x20 ||
+    codePoint === 0x9 ||
+    codePoint === 0xD ||
+    codePoint === 0xA
+  );
+};
+
+const isDigit = c => {
+  const codePoint = c.codePointAt(0);
+  return 48 <= codePoint && codePoint <= 57;
+};
+
+const readNumber = (string, cursor) => {
+  let i = cursor;
+  let number = '';
+  // none | sign | whole | decimal_point | decimal | e | exponent_sign | exponent
+  let state = 'none';
+  for (; i < string.length; i += 1) {
+    const c = string[i];
+    if (c === '+' || c === '-') {
+      if (state === 'none') {
+        state = 'sign'
+        number += c;
+        continue;
+      }
+      if (state === 'e') {
+        state === 'exponent_sign';
+        number += c;
+        continue;
+      }
+    }
+    if (isDigit(c)) {
+      if (state === 'none' || state === 'sign' || state === 'whole') {
+        state = 'whole';
+        number += c;
+        continue;
+      }
+      if (state === 'decimal_point' || state === 'decimal') {
+        state = 'decimal';
+        number += c;
+        continue;
+      }
+      if (state === 'e' || state === 'exponent_sign' || state === 'exponent') {
+        state = 'exponent';
+        number += c;
+        continue;
+      }
+    }
+    if (c === '.') {
+      if (state === 'none' || state === 'sign' || state === 'whole') {
+        state = 'decimal_point';
+        number += c;
+        continue;
+      }
+    }
+    if (c === 'E' || c == 'e') {
+      if (state === 'whole' || state === 'decimal_point' || state === 'decimal') {
+        state = 'e';
+        number += c;
+        continue;
+      }
+    }
+    break;
+  }
+  if (state === 'none' || state === 'sign' || state === 'e' || state === 'exponent_sign') {
+    return [i - 1, null];
+  }
+  // step back to delegate teration to parent loop
+  return [i - 1, Number(number)];
+};
+
+
+// TODO do not erase args in flushing after number reading this prevents handling commas
+const parsePathData = (string) => {
+  const commands = [];
+  let i = 0;
+  let command = null;
+  let args;
+  let argsCount;
+  // moveto should be leading command
+  const c = string.charAt(i);
+  for (; i < string.length; i += 1) {
+    const c = string.charAt(i);
+    // TODO forbid comma between commands
+    if (isWsp(c) || c === ',') {
+      continue;
+    }
+    if (isCommand(c)) {
+      if (command == null) {
+        // moveto should be leading command
+        if (c !== 'M' && c !== 'm') {
+          return commands;
+        }
+      } else {
+        // stop if previous command arguments are miscounted
+        if (argsCount !== 0 && args.length % argsCount !== 0) {
+          return commands;
+        }
+      }
+      command = c;
+      args = [];
+      argsCount = argsCountPerCommand[command];
+      if (argsCount === 0) {
+        commands.push({ name: command, args });
+      }
+      continue;
+    }
+    // avoid parsing arguments if no command detected
+    if (command == null) {
+      return commands;
+    }
+    // read next arg
+    let newCursor = i;
+    let number = null;
+    if (command === 'A' || command === 'a') {
+      const mod = args.length % argsCount;
+      if (mod === 0 || mod === 1) {
+        // allow only positive number without sign as first two arguments
+        if (c !== '+' && c !== '-') {
+          [newCursor, number] = readNumber(string, i);
+        }
+      }
+      if (mod === 2) {
+        [newCursor, number] = readNumber(string, i);
+      }
+      if (mod === 3 || mod === 4) {
+        // read flags
+        if (c === '0') {
+          number = 0;
+        }
+        if (c === '1') {
+          number = 1;
+        }
+      }
+      if (mod === 5 || mod === 6) {
+        [newCursor, number] = readNumber(string, i);
+      }
+    } else {
+      [newCursor, number] = readNumber(string, i);
+    }
+    if (number == null) {
+      return commands;
+    } else {
+      args.push(number);
+    }
+    i = newCursor;
+    // flush args
+    if (args.length >= argsCount && args.length % argsCount === 0) {
+      commands.push({ name: command, args });
+      // subsequent moveto coordinates are threated as implicit lineto commands
+      if (command === 'M') {
+        command = 'L';
+      }
+      if (command === 'm') {
+        command = 'l';
+      }
+      args = [];
+    }
+  }
+  if (args.length !== argsCount) {
+    return commands;
+  }
+  return commands;
+};
+exports.parsePathData = parsePathData;
diff --git a/plugins/_path.js b/plugins/_path.js
index 01c9fa7f7..6c72fe281 100644
--- a/plugins/_path.js
+++ b/plugins/_path.js
@@ -1,16 +1,8 @@
 'use strict';
 
-var rNumber = String.raw`[-+]?(?:\d*\.\d+|\d+\.?)(?:[eE][-+]?\d+)?\s*`,
-    rCommaWsp = String.raw`(?:\s,?\s*|,\s*)`,
-    rNumberCommaWsp = `(${rNumber})` + rCommaWsp,
-    rFlagCommaWsp = `([01])${rCommaWsp}?`,
-    rCoordinatePair = String.raw`(${rNumber})${rCommaWsp}?(${rNumber})`,
-    rArcSeq = (rNumberCommaWsp + '?').repeat(2) + rNumberCommaWsp + rFlagCommaWsp.repeat(2) + rCoordinatePair;
-
-var regPathInstructions = /([MmLlHhVvCcSsQqTtAaZz])\s*/,
-    regCoordinateSequence = new RegExp(rNumber, 'g'),
-    regArcArgumentSequence = new RegExp(rArcSeq, 'g'),
-    regNumericValues = /[-+]?(\d*\.\d+|\d+\.?)(?:[eE][-+]?\d+)?/g,
+const { parsePathData } = require('../lib/path.js');
+
+var regNumericValues = /[-+]?(\d*\.\d+|\d+\.?)(?:[eE][-+]?\d+)?/g,
     transform2js = require('./_transforms').transform2js,
     transformsMultiply = require('./_transforms').transformsMultiply,
     transformArc = require('./_transforms').transformArc,
@@ -29,77 +21,22 @@ var regPathInstructions = /([MmLlHhVvCcSsQqTtAaZz])\s*/,
  * @return {Array} output array
  */
 exports.path2js = function(path) {
-    if (path.pathJS) return path.pathJS;
-
-    var paramsLength = { // Number of parameters of every path command
-            H: 1, V: 1, M: 2, L: 2, T: 2, Q: 4, S: 4, C: 6, A: 7,
-            h: 1, v: 1, m: 2, l: 2, t: 2, q: 4, s: 4, c: 6, a: 7
-        },
-        pathData = [],   // JS representation of the path data
-        instruction, // current instruction context
-        startMoveto = false;
-
-    // splitting path string into array like ['M', '10 50', 'L', '20 30']
-    path.attr('d').value.split(regPathInstructions).forEach(function(data) {
-        if (!data) return;
-        if (!startMoveto) {
-            if (data == 'M' || data == 'm') {
-                startMoveto = true;
-            } else return;
-        }
-
-        // instruction item
-        if (regPathInstructions.test(data)) {
-            instruction = data;
-
-            // z - instruction w/o data
-            if (instruction == 'Z' || instruction == 'z') {
-                pathData.push({
-                    instruction: 'z'
-                });
-            }
-        // data item
-        } else {
-            if (instruction == 'A' || instruction == 'a') {
-                var newData = [];
-                for (var args; (args = regArcArgumentSequence.exec(data));) {
-                    for (var i = 1; i < args.length; i++) {
-                        newData.push(args[i]);
-                    }
-                }
-                data = newData;
-            } else {
-                data = data.match(regCoordinateSequence);
-            }
-            if (!data) return;
-
-            data = data.map(Number);
-            // Subsequent moveto pairs of coordinates are threated as implicit lineto commands
-            // https://www.w3.org/TR/SVG11/paths.html#PathDataMovetoCommands
-            if (instruction == 'M' || instruction == 'm') {
-                pathData.push({
-                    instruction: pathData.length == 0 ? 'M' : instruction,
-                    data: data.splice(0, 2)
-                });
-                instruction = instruction == 'M' ? 'L' : 'l';
-            }
-
-            for (var pair = paramsLength[instruction]; data.length;) {
-                pathData.push({
-                    instruction: instruction,
-                    data: data.splice(0, pair)
-                });
-            }
-        }
-    });
-
-    // First moveto is actually absolute. Subsequent coordinates were separated above.
-    if (pathData.length && pathData[0].instruction == 'm') {
-        pathData[0].instruction = 'M';
+  if (path.pathJS) return path.pathJS;
+  const pathData = [];   // JS representation of the path data
+  const commands = parsePathData(path.attr('d').value);
+  for (const { name, args } of commands) {
+    if (name === 'Z' || name === 'z') {
+      pathData.push({ instruction: 'z' });
+    } else {
+      pathData.push({ instruction: name, data: args });
     }
-    path.pathJS = pathData;
-
-    return pathData;
+  }
+  // First moveto is actually absolute. Subsequent coordinates were separated above.
+  if (pathData.length && pathData[0].instruction == 'm') {
+    pathData[0].instruction = 'M';
+  }
+  path.pathJS = pathData;
+  return pathData;
 };
 
 /**

From 2061c4027bb10f9225a35adc3361a6e352ec84bb Mon Sep 17 00:00:00 2001
From: Bogdan Chadkin <trysound@yandex.ru>
Date: Fri, 26 Feb 2021 18:12:08 +0300
Subject: [PATCH 02/12] Remove old code

---
 lib/path.js | 2 --
 1 file changed, 2 deletions(-)

diff --git a/lib/path.js b/lib/path.js
index 689cac68d..efe3cdd3b 100644
--- a/lib/path.js
+++ b/lib/path.js
@@ -111,8 +111,6 @@ const parsePathData = (string) => {
   let command = null;
   let args;
   let argsCount;
-  // moveto should be leading command
-  const c = string.charAt(i);
   for (; i < string.length; i += 1) {
     const c = string.charAt(i);
     // TODO forbid comma between commands

From 347d9c9bcaad6075d021a87b2c1587756799e089 Mon Sep 17 00:00:00 2001
From: Bogdan Chadkin <trysound@yandex.ru>
Date: Fri, 26 Feb 2021 18:14:56 +0300
Subject: [PATCH 03/12] fix comment

---
 lib/path.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/path.js b/lib/path.js
index efe3cdd3b..cce7da33a 100644
--- a/lib/path.js
+++ b/lib/path.js
@@ -99,7 +99,7 @@ const readNumber = (string, cursor) => {
   if (state === 'none' || state === 'sign' || state === 'e' || state === 'exponent_sign') {
     return [i - 1, null];
   }
-  // step back to delegate teration to parent loop
+  // step back to delegate iteration to parent loop
   return [i - 1, Number(number)];
 };
 

From 67b8944ce17ed19c1c1d41ccad2a4eaea9758075 Mon Sep 17 00:00:00 2001
From: Bogdan Chadkin <trysound@yandex.ru>
Date: Fri, 26 Feb 2021 20:13:20 +0300
Subject: [PATCH 04/12] Rename commands to pathData

---
 lib/path.js      | 18 +++++++++---------
 plugins/_path.js |  8 ++++----
 2 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/lib/path.js b/lib/path.js
index cce7da33a..b6bfa01ad 100644
--- a/lib/path.js
+++ b/lib/path.js
@@ -106,7 +106,7 @@ const readNumber = (string, cursor) => {
 
 // TODO do not erase args in flushing after number reading this prevents handling commas
 const parsePathData = (string) => {
-  const commands = [];
+  const pathData = [];
   let i = 0;
   let command = null;
   let args;
@@ -121,25 +121,25 @@ const parsePathData = (string) => {
       if (command == null) {
         // moveto should be leading command
         if (c !== 'M' && c !== 'm') {
-          return commands;
+          return pathData;
         }
       } else {
         // stop if previous command arguments are miscounted
         if (argsCount !== 0 && args.length % argsCount !== 0) {
-          return commands;
+          return pathData;
         }
       }
       command = c;
       args = [];
       argsCount = argsCountPerCommand[command];
       if (argsCount === 0) {
-        commands.push({ name: command, args });
+        pathData.push({ command, args });
       }
       continue;
     }
     // avoid parsing arguments if no command detected
     if (command == null) {
-      return commands;
+      return pathData;
     }
     // read next arg
     let newCursor = i;
@@ -171,14 +171,14 @@ const parsePathData = (string) => {
       [newCursor, number] = readNumber(string, i);
     }
     if (number == null) {
-      return commands;
+      return pathData;
     } else {
       args.push(number);
     }
     i = newCursor;
     // flush args
     if (args.length >= argsCount && args.length % argsCount === 0) {
-      commands.push({ name: command, args });
+      pathData.push({ command, args });
       // subsequent moveto coordinates are threated as implicit lineto commands
       if (command === 'M') {
         command = 'L';
@@ -190,8 +190,8 @@ const parsePathData = (string) => {
     }
   }
   if (args.length !== argsCount) {
-    return commands;
+    return pathData;
   }
-  return commands;
+  return pathData;
 };
 exports.parsePathData = parsePathData;
diff --git a/plugins/_path.js b/plugins/_path.js
index 6c72fe281..00ecf5a4e 100644
--- a/plugins/_path.js
+++ b/plugins/_path.js
@@ -23,12 +23,12 @@ var regNumericValues = /[-+]?(\d*\.\d+|\d+\.?)(?:[eE][-+]?\d+)?/g,
 exports.path2js = function(path) {
   if (path.pathJS) return path.pathJS;
   const pathData = [];   // JS representation of the path data
-  const commands = parsePathData(path.attr('d').value);
-  for (const { name, args } of commands) {
-    if (name === 'Z' || name === 'z') {
+  const newPathData = parsePathData(path.attr('d').value);
+  for (const { command, args } of newPathData) {
+    if (command === 'Z' || command === 'z') {
       pathData.push({ instruction: 'z' });
     } else {
-      pathData.push({ instruction: name, data: args });
+      pathData.push({ instruction: command, data: args });
     }
   }
   // First moveto is actually absolute. Subsequent coordinates were separated above.

From aff622beb9715d5375ee774f36f1586d69a17198 Mon Sep 17 00:00:00 2001
From: Bogdan Chadkin <trysound@yandex.ru>
Date: Fri, 26 Feb 2021 22:10:54 +0300
Subject: [PATCH 05/12] Handle commas according to spec

---
 lib/path.js      | 23 ++++++++++++++++++-----
 lib/path.test.js | 49 ++++++++++++++++++++++++++++++++++++++++++++++++
 package.json     |  2 +-
 3 files changed, 68 insertions(+), 6 deletions(-)
 create mode 100644 lib/path.test.js

diff --git a/lib/path.js b/lib/path.js
index b6bfa01ad..0c4ece5cb 100644
--- a/lib/path.js
+++ b/lib/path.js
@@ -104,20 +104,31 @@ const readNumber = (string, cursor) => {
 };
 
 
-// TODO do not erase args in flushing after number reading this prevents handling commas
 const parsePathData = (string) => {
   const pathData = [];
   let i = 0;
   let command = null;
   let args;
   let argsCount;
+  let argsInSequenceCount = 0;
+  let hadComma = false;
   for (; i < string.length; i += 1) {
     const c = string.charAt(i);
-    // TODO forbid comma between commands
-    if (isWsp(c) || c === ',') {
+    if (isWsp(c)) {
+      continue;
+    }
+    // allow comma only between arguments
+    if (argsInSequenceCount !== 0 && c === ',') {
+      if (hadComma) {
+        break;
+      }
+      hadComma = true;
       continue;
     }
     if (isCommand(c)) {
+      if (hadComma) {
+        return pathData;
+      }
       if (command == null) {
         // moveto should be leading command
         if (c !== 'M' && c !== 'm') {
@@ -132,6 +143,7 @@ const parsePathData = (string) => {
       command = c;
       args = [];
       argsCount = argsCountPerCommand[command];
+      argsInSequenceCount = 0;
       if (argsCount === 0) {
         pathData.push({ command, args });
       }
@@ -172,9 +184,10 @@ const parsePathData = (string) => {
     }
     if (number == null) {
       return pathData;
-    } else {
-      args.push(number);
     }
+    args.push(number);
+    argsInSequenceCount += 1;
+    hadComma = false;
     i = newCursor;
     // flush args
     if (args.length >= argsCount && args.length % argsCount === 0) {
diff --git a/lib/path.test.js b/lib/path.test.js
new file mode 100644
index 000000000..6956749fd
--- /dev/null
+++ b/lib/path.test.js
@@ -0,0 +1,49 @@
+'use strict';
+
+const { expect } = require('chai');
+const { parsePathData } = require('./path.js');
+
+describe('parse path data', () => {
+  it('should allow spaces between commands', () => {
+    expect(parsePathData('M0 10 L \n\r\t20 30')).to.deep.equal([
+      { command: 'M', args: [0, 10] },
+      { command: 'L', args: [20, 30] },
+    ]);
+  });
+  it('should allow spaces and commas between arguments', () => {
+    expect(parsePathData('M0 , 10 L 20 \n\r\t30,40,50')).to.deep.equal([
+      { command: 'M', args: [0, 10] },
+      { command: 'L', args: [20, 30] },
+      { command: 'L', args: [40, 50] },
+    ]);
+  });
+  it('should forbid commas before commands', () => {
+    expect(parsePathData(', M0 10')).to.deep.equal([]);
+  });
+  it('should forbid commas between commands', () => {
+    expect(parsePathData('M0,10 , L 20,30')).to.deep.equal([
+      { command: 'M', args: [0, 10] },
+    ]);
+  });
+  it('should forbid commas between command name and argument', () => {
+    expect(parsePathData('M0,10 L,20,30')).to.deep.equal([
+      { command: 'M', args: [0, 10] },
+    ]);
+  });
+  it('should forbid multipe commas in a row', () => {
+    expect(parsePathData('M0 , , 10')).to.deep.equal([]);
+  });
+  it('should stop when unknown char appears', () => {
+    expect(parsePathData('M0 10 , L 20 #40')).to.deep.equal([
+      { command: 'M', args: [0, 10] },
+    ]);
+  });
+  it('should stop when not enough arguments', () => {
+    expect(parsePathData('M0 10 L 20 L 30 40')).to.deep.equal([
+      { command: 'M', args: [0, 10] },
+    ]);
+  });
+  it('should stop if moveto not the first command', () => {
+    expect(parsePathData('L 10 20')).to.deep.equal([]);
+  });
+});
diff --git a/package.json b/package.json
index 4d19409b1..fb2f7db06 100644
--- a/package.json
+++ b/package.json
@@ -49,7 +49,7 @@
     "dist"
   ],
   "scripts": {
-    "test": "c8 --reporter=html --reporter=text mocha \"test/*/_index.js\"",
+    "test": "c8 --reporter=html --reporter=text mocha \"test/*/_index.js\" \"**/*.test.js\" --ignore=\"node_modules/**\"",
     "lint": "eslint .",
     "test-browser": "rollup -c && node ./test/browser.js",
     "prepublishOnly": "rm -rf dist && rollup -c"

From 32c50fbe706873cfc57b59b7842d6d6ed7dfc635 Mon Sep 17 00:00:00 2001
From: Bogdan Chadkin <trysound@yandex.ru>
Date: Fri, 26 Feb 2021 22:12:19 +0300
Subject: [PATCH 06/12] Group arc arguments parsing

---
 lib/path.js | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/lib/path.js b/lib/path.js
index 0c4ece5cb..d0af3d6f1 100644
--- a/lib/path.js
+++ b/lib/path.js
@@ -164,7 +164,7 @@ const parsePathData = (string) => {
           [newCursor, number] = readNumber(string, i);
         }
       }
-      if (mod === 2) {
+      if (mod === 2 || mod === 5 || mod === 6) {
         [newCursor, number] = readNumber(string, i);
       }
       if (mod === 3 || mod === 4) {
@@ -176,9 +176,6 @@ const parsePathData = (string) => {
           number = 1;
         }
       }
-      if (mod === 5 || mod === 6) {
-        [newCursor, number] = readNumber(string, i);
-      }
     } else {
       [newCursor, number] = readNumber(string, i);
     }

From f01fa7ba20e04837d1bfcf9dedb6464eced4a99b Mon Sep 17 00:00:00 2001
From: Bogdan Chadkin <trysound@yandex.ru>
Date: Fri, 26 Feb 2021 22:15:34 +0300
Subject: [PATCH 07/12] Fix lint

---
 package.json | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/package.json b/package.json
index fb2f7db06..2512b6ce0 100644
--- a/package.json
+++ b/package.json
@@ -83,7 +83,8 @@
       },
       {
         "files": [
-          "test/**/*.js"
+          "test/**/*.js",
+          "**/*.test.js"
         ],
         "env": {
           "mocha": true

From 26a3fd85ff66b7b374a2ba631d993b1e8302f31e Mon Sep 17 00:00:00 2001
From: Bogdan Chadkin <trysound@yandex.ru>
Date: Fri, 26 Feb 2021 23:49:21 +0300
Subject: [PATCH 08/12] Fix invalid number parsing

---
 lib/path.js      | 27 +++++++++++++++------------
 lib/path.test.js |  4 ++++
 2 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/lib/path.js b/lib/path.js
index d0af3d6f1..72505e544 100644
--- a/lib/path.js
+++ b/lib/path.js
@@ -46,7 +46,7 @@ const isDigit = c => {
 
 const readNumber = (string, cursor) => {
   let i = cursor;
-  let number = '';
+  let value = '';
   // none | sign | whole | decimal_point | decimal | e | exponent_sign | exponent
   let state = 'none';
   for (; i < string.length; i += 1) {
@@ -54,53 +54,55 @@ const readNumber = (string, cursor) => {
     if (c === '+' || c === '-') {
       if (state === 'none') {
         state = 'sign'
-        number += c;
+        value += c;
         continue;
       }
       if (state === 'e') {
         state === 'exponent_sign';
-        number += c;
+        value += c;
         continue;
       }
     }
     if (isDigit(c)) {
       if (state === 'none' || state === 'sign' || state === 'whole') {
         state = 'whole';
-        number += c;
+        value += c;
         continue;
       }
       if (state === 'decimal_point' || state === 'decimal') {
         state = 'decimal';
-        number += c;
+        value += c;
         continue;
       }
       if (state === 'e' || state === 'exponent_sign' || state === 'exponent') {
         state = 'exponent';
-        number += c;
+        value += c;
         continue;
       }
     }
     if (c === '.') {
       if (state === 'none' || state === 'sign' || state === 'whole') {
         state = 'decimal_point';
-        number += c;
+        value += c;
         continue;
       }
     }
     if (c === 'E' || c == 'e') {
       if (state === 'whole' || state === 'decimal_point' || state === 'decimal') {
         state = 'e';
-        number += c;
+        value += c;
         continue;
       }
     }
     break;
   }
-  if (state === 'none' || state === 'sign' || state === 'e' || state === 'exponent_sign') {
-    return [i - 1, null];
+  const number = Number.parseFloat(value);
+  if (Number.isNaN(number)) {
+    return [cursor, null];
+  } else {
+    // step back to delegate iteration to parent loop
+    return [i - 1, number];
   }
-  // step back to delegate iteration to parent loop
-  return [i - 1, Number(number)];
 };
 
 
@@ -144,6 +146,7 @@ const parsePathData = (string) => {
       args = [];
       argsCount = argsCountPerCommand[command];
       argsInSequenceCount = 0;
+      // flush command without args
       if (argsCount === 0) {
         pathData.push({ command, args });
       }
diff --git a/lib/path.test.js b/lib/path.test.js
index 6956749fd..66a2887b2 100644
--- a/lib/path.test.js
+++ b/lib/path.test.js
@@ -45,5 +45,9 @@ describe('parse path data', () => {
   });
   it('should stop if moveto not the first command', () => {
     expect(parsePathData('L 10 20')).to.deep.equal([]);
+    expect(parsePathData('10 20')).to.deep.equal([]);
+  });
+  it('should stop on invalid numbers', () => {
+    expect(parsePathData('M ...')).to.deep.equal([]);
   });
 });

From 9bd69d35684441c4da2a6d9fd3fb481060952f7f Mon Sep 17 00:00:00 2001
From: Bogdan Chadkin <trysound@yandex.ru>
Date: Sat, 27 Feb 2021 00:09:16 +0300
Subject: [PATCH 09/12] Slightly simplify arcs parsing

---
 lib/path.js      | 10 +++++-----
 lib/path.test.js | 23 +++++++++++++++++++++++
 2 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/lib/path.js b/lib/path.js
index 72505e544..9ccdde73e 100644
--- a/lib/path.js
+++ b/lib/path.js
@@ -156,21 +156,21 @@ const parsePathData = (string) => {
     if (command == null) {
       return pathData;
     }
-    // read next arg
+    // read next argument
     let newCursor = i;
     let number = null;
     if (command === 'A' || command === 'a') {
-      const mod = args.length % argsCount;
-      if (mod === 0 || mod === 1) {
+      const position = args.length;
+      if (position === 0 || position === 1) {
         // allow only positive number without sign as first two arguments
         if (c !== '+' && c !== '-') {
           [newCursor, number] = readNumber(string, i);
         }
       }
-      if (mod === 2 || mod === 5 || mod === 6) {
+      if (position === 2 || position === 5 || position === 6) {
         [newCursor, number] = readNumber(string, i);
       }
-      if (mod === 3 || mod === 4) {
+      if (position === 3 || position === 4) {
         // read flags
         if (c === '0') {
           number = 0;
diff --git a/lib/path.test.js b/lib/path.test.js
index 66a2887b2..daa1bfe32 100644
--- a/lib/path.test.js
+++ b/lib/path.test.js
@@ -50,4 +50,27 @@ describe('parse path data', () => {
   it('should stop on invalid numbers', () => {
     expect(parsePathData('M ...')).to.deep.equal([]);
   });
+  it('should handle arcs', () => {
+    expect(
+      parsePathData(
+        `
+          M600,350
+          l 50,-25
+          a25,25 -30 0,1 50,-25
+          25,50 -30 0,1 50,-25
+          25,75 -30 0,1 50,-25
+          a25,100 -30 0,1 50,-25
+          l 50,-25
+        `
+      )
+    ).to.deep.equal([
+      { "command": "M", "args": [600, 350] },
+      { "command": "l", "args": [50, -25] },
+      { "command": "a", "args": [25, 25, -30, 0, 1, 50, -25] },
+      { "command": "a", "args": [25, 50, -30, 0, 1, 50, -25] },
+      { "command": "a", "args": [25, 75, -30, 0, 1, 50, -25] },
+      { "command": "a", "args": [25, 100, -30, 0, 1, 50, -25] },
+      { "command": "l", "args": [50, -25] },
+    ]);
+  });
 });

From 9f8675cf018dbb3ee5a4f144b896b2efe0ca3154 Mon Sep 17 00:00:00 2001
From: Bogdan Chadkin <trysound@yandex.ru>
Date: Sat, 27 Feb 2021 00:19:56 +0300
Subject: [PATCH 10/12] Remove useless mod

---
 lib/path.js | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/lib/path.js b/lib/path.js
index 9ccdde73e..63dfee57b 100644
--- a/lib/path.js
+++ b/lib/path.js
@@ -137,8 +137,8 @@ const parsePathData = (string) => {
           return pathData;
         }
       } else {
-        // stop if previous command arguments are miscounted
-        if (argsCount !== 0 && args.length % argsCount !== 0) {
+        // stop if previous command arguments are not flushed
+        if (args.length !== 0) {
           return pathData;
         }
       }
@@ -146,7 +146,7 @@ const parsePathData = (string) => {
       args = [];
       argsCount = argsCountPerCommand[command];
       argsInSequenceCount = 0;
-      // flush command without args
+      // flush command without arguments
       if (argsCount === 0) {
         pathData.push({ command, args });
       }
@@ -189,8 +189,8 @@ const parsePathData = (string) => {
     argsInSequenceCount += 1;
     hadComma = false;
     i = newCursor;
-    // flush args
-    if (args.length >= argsCount && args.length % argsCount === 0) {
+    // flush arguments when necessary count is reached
+    if (args.length === argsCount) {
       pathData.push({ command, args });
       // subsequent moveto coordinates are threated as implicit lineto commands
       if (command === 'M') {
@@ -202,9 +202,6 @@ const parsePathData = (string) => {
       args = [];
     }
   }
-  if (args.length !== argsCount) {
-    return pathData;
-  }
   return pathData;
 };
 exports.parsePathData = parsePathData;

From bc23d2f108774acfb71a436994a2a57a13443cf7 Mon Sep 17 00:00:00 2001
From: Bogdan Chadkin <trysound@yandex.ru>
Date: Sat, 27 Feb 2021 00:24:29 +0300
Subject: [PATCH 11/12] Simplify comma detection

---
 lib/path.js | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/lib/path.js b/lib/path.js
index 63dfee57b..5b4a89665 100644
--- a/lib/path.js
+++ b/lib/path.js
@@ -112,7 +112,7 @@ const parsePathData = (string) => {
   let command = null;
   let args;
   let argsCount;
-  let argsInSequenceCount = 0;
+  let canHaveComma = false;
   let hadComma = false;
   for (; i < string.length; i += 1) {
     const c = string.charAt(i);
@@ -120,7 +120,7 @@ const parsePathData = (string) => {
       continue;
     }
     // allow comma only between arguments
-    if (argsInSequenceCount !== 0 && c === ',') {
+    if (canHaveComma && c === ',') {
       if (hadComma) {
         break;
       }
@@ -145,7 +145,7 @@ const parsePathData = (string) => {
       command = c;
       args = [];
       argsCount = argsCountPerCommand[command];
-      argsInSequenceCount = 0;
+      canHaveComma = false;
       // flush command without arguments
       if (argsCount === 0) {
         pathData.push({ command, args });
@@ -186,7 +186,7 @@ const parsePathData = (string) => {
       return pathData;
     }
     args.push(number);
-    argsInSequenceCount += 1;
+    canHaveComma = true;
     hadComma = false;
     i = newCursor;
     // flush arguments when necessary count is reached

From 651aa6918f82eb7ea16af2f5df8c32d063a28e52 Mon Sep 17 00:00:00 2001
From: Bogdan Chadkin <trysound@yandex.ru>
Date: Sun, 28 Feb 2021 15:37:37 +0300
Subject: [PATCH 12/12] Fix formatting

---
 lib/path.js      | 21 ++++++++++++---------
 lib/path.test.js | 14 +++++++-------
 2 files changed, 19 insertions(+), 16 deletions(-)

diff --git a/lib/path.js b/lib/path.js
index 5b4a89665..9b79550b0 100644
--- a/lib/path.js
+++ b/lib/path.js
@@ -22,24 +22,24 @@ const argsCountPerCommand = {
   T: 2,
   t: 2,
   A: 7,
-  a: 7
+  a: 7,
 };
 
-const isCommand = c => {
+const isCommand = (c) => {
   return c in argsCountPerCommand;
 };
 
-const isWsp = c => {
+const isWsp = (c) => {
   const codePoint = c.codePointAt(0);
   return (
     codePoint === 0x20 ||
     codePoint === 0x9 ||
-    codePoint === 0xD ||
-    codePoint === 0xA
+    codePoint === 0xd ||
+    codePoint === 0xa
   );
 };
 
-const isDigit = c => {
+const isDigit = (c) => {
   const codePoint = c.codePointAt(0);
   return 48 <= codePoint && codePoint <= 57;
 };
@@ -53,7 +53,7 @@ const readNumber = (string, cursor) => {
     const c = string[i];
     if (c === '+' || c === '-') {
       if (state === 'none') {
-        state = 'sign'
+        state = 'sign';
         value += c;
         continue;
       }
@@ -88,7 +88,11 @@ const readNumber = (string, cursor) => {
       }
     }
     if (c === 'E' || c == 'e') {
-      if (state === 'whole' || state === 'decimal_point' || state === 'decimal') {
+      if (
+        state === 'whole' ||
+        state === 'decimal_point' ||
+        state === 'decimal'
+      ) {
         state = 'e';
         value += c;
         continue;
@@ -105,7 +109,6 @@ const readNumber = (string, cursor) => {
   }
 };
 
-
 const parsePathData = (string) => {
   const pathData = [];
   let i = 0;
diff --git a/lib/path.test.js b/lib/path.test.js
index daa1bfe32..bcb1dbd48 100644
--- a/lib/path.test.js
+++ b/lib/path.test.js
@@ -64,13 +64,13 @@ describe('parse path data', () => {
         `
       )
     ).to.deep.equal([
-      { "command": "M", "args": [600, 350] },
-      { "command": "l", "args": [50, -25] },
-      { "command": "a", "args": [25, 25, -30, 0, 1, 50, -25] },
-      { "command": "a", "args": [25, 50, -30, 0, 1, 50, -25] },
-      { "command": "a", "args": [25, 75, -30, 0, 1, 50, -25] },
-      { "command": "a", "args": [25, 100, -30, 0, 1, 50, -25] },
-      { "command": "l", "args": [50, -25] },
+      { command: 'M', args: [600, 350] },
+      { command: 'l', args: [50, -25] },
+      { command: 'a', args: [25, 25, -30, 0, 1, 50, -25] },
+      { command: 'a', args: [25, 50, -30, 0, 1, 50, -25] },
+      { command: 'a', args: [25, 75, -30, 0, 1, 50, -25] },
+      { command: 'a', args: [25, 100, -30, 0, 1, 50, -25] },
+      { command: 'l', args: [50, -25] },
     ]);
   });
 });