add lisp packages

lisp/emacs-application-framework/app/mermaid/node_modules/d3-path/LICENSE

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+Copyright 2015-2016 Mike Bostock
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification,
+are permitted provided that the following conditions are met:
+
+* Redistributions of source code must retain the above copyright notice, this
+  list of conditions and the following disclaimer.
+
+* Redistributions in binary form must reproduce the above copyright notice,
+  this list of conditions and the following disclaimer in the documentation
+  and/or other materials provided with the distribution.
+
+* Neither the name of the author nor the names of contributors may be used to
+  endorse or promote products derived from this software without specific prior
+  written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

lisp/emacs-application-framework/app/mermaid/node_modules/d3-path/README.md

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+# d3-path
+
+Say you have some code that draws to a 2D canvas:
+
+```js
+function drawCircle(context, radius) {
+  context.moveTo(radius, 0);
+  context.arc(0, 0, radius, 0, 2 * Math.PI);
+}
+```
+
+The d3-path module lets you take this exact code and additionally render to [SVG](http://www.w3.org/TR/SVG/paths.html). It works by [serializing](#path_toString) [CanvasPathMethods](http://www.w3.org/TR/2dcontext/#canvaspathmethods) calls to [SVG path data](http://www.w3.org/TR/SVG/paths.html#PathData). For example:
+
+```js
+var context = d3.path();
+drawCircle(context, 40);
+pathElement.setAttribute("d", context.toString());
+```
+
+Now code you write once can be used with both Canvas (for performance) and SVG (for convenience). For a practical example, see [d3-shape](https://github.com/d3/d3-shape).
+
+## Installing
+
+If you use NPM, `npm install d3-path`. Otherwise, download the [latest release](https://github.com/d3/d3-path/releases/latest). You can also load directly from [d3js.org](https://d3js.org), either as a [standalone library](https://d3js.org/d3-path.v1.min.js) or as part of [D3 4.0](https://github.com/d3/d3). AMD, CommonJS, and vanilla environments are supported. In vanilla, a `d3` global is exported:
+
+```html
+<script src="https://d3js.org/d3-path.v1.min.js"></script>
+<script>
+
+var path = d3.path();
+path.moveTo(1, 2);
+path.lineTo(3, 4);
+path.closePath();
+
+</script>
+```
+
+## API Reference
+
+<a name="path" href="#path">#</a> d3.<b>path</b>() · [Source](https://github.com/d3/d3-path/blob/master/src/path.js), [Examples](https://observablehq.com/@d3/d3-path)
+
+Constructs a new path serializer that implements [CanvasPathMethods](http://www.w3.org/TR/2dcontext/#canvaspathmethods).
+
+<a name="path_moveTo" href="#path_moveTo">#</a> <i>path</i>.<b>moveTo</b>(<i>x</i>, <i>y</i>)
+
+Move to the specified point ⟨*x*, *y*⟩. Equivalent to [*context*.moveTo](http://www.w3.org/TR/2dcontext/#dom-context-2d-moveto) and SVG’s [“moveto” command](http://www.w3.org/TR/SVG/paths.html#PathDataMovetoCommands).
+
+<a name="path_closePath" href="#path_closePath">#</A> <i>path</i>.<b>closePath</b>()
+
+Ends the current subpath and causes an automatic straight line to be drawn from the current point to the initial point of the current subpath. Equivalent to [*context*.closePath](http://www.w3.org/TR/2dcontext/#dom-context-2d-closepath) and SVG’s [“closepath” command](http://www.w3.org/TR/SVG/paths.html#PathDataClosePathCommand).
+
+<a name="path_lineTo" href="#path_lineTo">#</a> <i>path</i>.<b>lineTo</b>(<i>x</i>, <i>y</i>)
+
+Draws a straight line from the current point to the specified point ⟨*x*, *y*⟩. Equivalent to [*context*.lineTo](http://www.w3.org/TR/2dcontext/#dom-context-2d-lineto) and SVG’s [“lineto” command](http://www.w3.org/TR/SVG/paths.html#PathDataLinetoCommands).
+
+<a name="path_quadraticCurveTo" href="#path_quadraticCurveTo">#</a> <i>path</i>.<b>quadraticCurveTo</b>(<i>cpx</i>, <i>cpy</i>, <i>x</i>, <i>y</i>)
+
+Draws a quadratic Bézier segment from the current point to the specified point ⟨*x*, *y*⟩, with the specified control point ⟨*cpx*, *cpy*⟩. Equivalent to [*context*.quadraticCurveTo](http://www.w3.org/TR/2dcontext/#dom-context-2d-quadraticcurveto) and SVG’s [quadratic Bézier curve commands](http://www.w3.org/TR/SVG/paths.html#PathDataQuadraticBezierCommands).
+
+<a name="path_bezierCurveTo" href="#path_bezierCurveTo">#</a> <i>path</i>.<b>bezierCurveTo</b>(<i>cpx1</i>, <i>cpy1</i>, <i>cpx2</i>, <i>cpy2</i>, <i>x</i>, <i>y</i>)
+
+Draws a cubic Bézier segment from the current point to the specified point ⟨*x*, *y*⟩, with the specified control points ⟨*cpx1*, *cpy1*⟩ and ⟨*cpx2*, *cpy2*⟩. Equivalent to [*context*.bezierCurveTo](http://www.w3.org/TR/2dcontext/#dom-context-2d-beziercurveto) and SVG’s [cubic Bézier curve commands](http://www.w3.org/TR/SVG/paths.html#PathDataCubicBezierCommands).
+
+<a name="path_arcTo" href="#path_arcTo">#</a> <i>path</i>.<b>arcTo</b>(<i>x1</i>, <i>y1</i>, <i>x2</i>, <i>y2</i>, <i>radius</i>)
+
+Draws a circular arc segment with the specified *radius* that starts tangent to the line between the current point and the specified point ⟨*x1*, *y1*⟩ and ends tangent to the line between the specified points ⟨*x1*, *y1*⟩ and ⟨*x2*, *y2*⟩. If the first tangent point is not equal to the current point, a straight line is drawn between the current point and the first tangent point. Equivalent to [*context*.arcTo](http://www.w3.org/TR/2dcontext/#dom-context-2d-arcto) and uses SVG’s [elliptical arc curve commands](http://www.w3.org/TR/SVG/paths.html#PathDataEllipticalArcCommands).
+
+<a name="path_arc" href="#path_arc">#</a> <i>path</i>.<b>arc</b>(<i>x</i>, <i>y</i>, <i>radius</i>, <i>startAngle</i>, <i>endAngle</i>[, <i>anticlockwise</i>])
+
+Draws a circular arc segment with the specified center ⟨*x*, *y*⟩, *radius*, *startAngle* and *endAngle*. If *anticlockwise* is true, the arc is drawn in the anticlockwise direction; otherwise, it is drawn in the clockwise direction. If the current point is not equal to the starting point of the arc, a straight line is drawn from the current point to the start of the arc. Equivalent to [*context*.arc](http://www.w3.org/TR/2dcontext/#dom-context-2d-arc) and uses SVG’s [elliptical arc curve commands](http://www.w3.org/TR/SVG/paths.html#PathDataEllipticalArcCommands).
+
+<a name="path_rect" href="#path_rect">#</a> <i>path</i>.<b>rect</b>(<i>x</i>, <i>y</i>, <i>w</i>, <i>h</i>)
+
+Creates a new subpath containing just the four points ⟨*x*, *y*⟩, ⟨*x* + *w*, *y*⟩, ⟨*x* + *w*, *y* + *h*⟩, ⟨*x*, *y* + *h*⟩, with those four points connected by straight lines, and then marks the subpath as closed. Equivalent to [*context*.rect](http://www.w3.org/TR/2dcontext/#dom-context-2d-rect) and uses SVG’s [“lineto” commands](http://www.w3.org/TR/SVG/paths.html#PathDataLinetoCommands).
+
+<a name="path_toString" href="#path_toString">#</a> <i>path</i>.<b>toString</b>()
+
+Returns the string representation of this *path* according to SVG’s [path data specification](http://www.w3.org/TR/SVG/paths.html#PathData).

lisp/emacs-application-framework/app/mermaid/node_modules/d3-path/dist/d3-path.js

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+// https://d3js.org/d3-path/ v1.0.9 Copyright 2019 Mike Bostock
+(function (global, factory) {
+typeof exports === 'object' && typeof module !== 'undefined' ? factory(exports) :
+typeof define === 'function' && define.amd ? define(['exports'], factory) :
+(global = global || self, factory(global.d3 = global.d3 || {}));
+}(this, function (exports) { 'use strict';
+
+var pi = Math.PI,
+    tau = 2 * pi,
+    epsilon = 1e-6,
+    tauEpsilon = tau - epsilon;
+
+function Path() {
+  this._x0 = this._y0 = // start of current subpath
+  this._x1 = this._y1 = null; // end of current subpath
+  this._ = "";
+}
+
+function path() {
+  return new Path;
+}
+
+Path.prototype = path.prototype = {
+  constructor: Path,
+  moveTo: function(x, y) {
+    this._ += "M" + (this._x0 = this._x1 = +x) + "," + (this._y0 = this._y1 = +y);
+  },
+  closePath: function() {
+    if (this._x1 !== null) {
+      this._x1 = this._x0, this._y1 = this._y0;
+      this._ += "Z";
+    }
+  },
+  lineTo: function(x, y) {
+    this._ += "L" + (this._x1 = +x) + "," + (this._y1 = +y);
+  },
+  quadraticCurveTo: function(x1, y1, x, y) {
+    this._ += "Q" + (+x1) + "," + (+y1) + "," + (this._x1 = +x) + "," + (this._y1 = +y);
+  },
+  bezierCurveTo: function(x1, y1, x2, y2, x, y) {
+    this._ += "C" + (+x1) + "," + (+y1) + "," + (+x2) + "," + (+y2) + "," + (this._x1 = +x) + "," + (this._y1 = +y);
+  },
+  arcTo: function(x1, y1, x2, y2, r) {
+    x1 = +x1, y1 = +y1, x2 = +x2, y2 = +y2, r = +r;
+    var x0 = this._x1,
+        y0 = this._y1,
+        x21 = x2 - x1,
+        y21 = y2 - y1,
+        x01 = x0 - x1,
+        y01 = y0 - y1,
+        l01_2 = x01 * x01 + y01 * y01;
+
+    // Is the radius negative? Error.
+    if (r < 0) throw new Error("negative radius: " + r);
+
+    // Is this path empty? Move to (x1,y1).
+    if (this._x1 === null) {
+      this._ += "M" + (this._x1 = x1) + "," + (this._y1 = y1);
+    }
+
+    // Or, is (x1,y1) coincident with (x0,y0)? Do nothing.
+    else if (!(l01_2 > epsilon));
+
+    // Or, are (x0,y0), (x1,y1) and (x2,y2) collinear?
+    // Equivalently, is (x1,y1) coincident with (x2,y2)?
+    // Or, is the radius zero? Line to (x1,y1).
+    else if (!(Math.abs(y01 * x21 - y21 * x01) > epsilon) || !r) {
+      this._ += "L" + (this._x1 = x1) + "," + (this._y1 = y1);
+    }
+
+    // Otherwise, draw an arc!
+    else {
+      var x20 = x2 - x0,
+          y20 = y2 - y0,
+          l21_2 = x21 * x21 + y21 * y21,
+          l20_2 = x20 * x20 + y20 * y20,
+          l21 = Math.sqrt(l21_2),
+          l01 = Math.sqrt(l01_2),
+          l = r * Math.tan((pi - Math.acos((l21_2 + l01_2 - l20_2) / (2 * l21 * l01))) / 2),
+          t01 = l / l01,
+          t21 = l / l21;
+
+      // If the start tangent is not coincident with (x0,y0), line to.
+      if (Math.abs(t01 - 1) > epsilon) {
+        this._ += "L" + (x1 + t01 * x01) + "," + (y1 + t01 * y01);
+      }
+
+      this._ += "A" + r + "," + r + ",0,0," + (+(y01 * x20 > x01 * y20)) + "," + (this._x1 = x1 + t21 * x21) + "," + (this._y1 = y1 + t21 * y21);
+    }
+  },
+  arc: function(x, y, r, a0, a1, ccw) {
+    x = +x, y = +y, r = +r, ccw = !!ccw;
+    var dx = r * Math.cos(a0),
+        dy = r * Math.sin(a0),
+        x0 = x + dx,
+        y0 = y + dy,
+        cw = 1 ^ ccw,
+        da = ccw ? a0 - a1 : a1 - a0;
+
+    // Is the radius negative? Error.
+    if (r < 0) throw new Error("negative radius: " + r);
+
+    // Is this path empty? Move to (x0,y0).
+    if (this._x1 === null) {
+      this._ += "M" + x0 + "," + y0;
+    }
+
+    // Or, is (x0,y0) not coincident with the previous point? Line to (x0,y0).
+    else if (Math.abs(this._x1 - x0) > epsilon || Math.abs(this._y1 - y0) > epsilon) {
+      this._ += "L" + x0 + "," + y0;
+    }
+
+    // Is this arc empty? We’re done.
+    if (!r) return;
+
+    // Does the angle go the wrong way? Flip the direction.
+    if (da < 0) da = da % tau + tau;
+
+    // Is this a complete circle? Draw two arcs to complete the circle.
+    if (da > tauEpsilon) {
+      this._ += "A" + r + "," + r + ",0,1," + cw + "," + (x - dx) + "," + (y - dy) + "A" + r + "," + r + ",0,1," + cw + "," + (this._x1 = x0) + "," + (this._y1 = y0);
+    }
+
+    // Is this arc non-empty? Draw an arc!
+    else if (da > epsilon) {
+      this._ += "A" + r + "," + r + ",0," + (+(da >= pi)) + "," + cw + "," + (this._x1 = x + r * Math.cos(a1)) + "," + (this._y1 = y + r * Math.sin(a1));
+    }
+  },
+  rect: function(x, y, w, h) {
+    this._ += "M" + (this._x0 = this._x1 = +x) + "," + (this._y0 = this._y1 = +y) + "h" + (+w) + "v" + (+h) + "h" + (-w) + "Z";
+  },
+  toString: function() {
+    return this._;
+  }
+};
+
+exports.path = path;
+
+Object.defineProperty(exports, '__esModule', { value: true });
+
+}));

lisp/emacs-application-framework/app/mermaid/node_modules/d3-path/dist/d3-path.min.js

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+// https://d3js.org/d3-path/ v1.0.9 Copyright 2019 Mike Bostock
+!function(t,i){"object"==typeof exports&&"undefined"!=typeof module?i(exports):"function"==typeof define&&define.amd?define(["exports"],i):i((t=t||self).d3=t.d3||{})}(this,function(t){"use strict";var i=Math.PI,s=2*i,h=s-1e-6;function e(){this._x0=this._y0=this._x1=this._y1=null,this._=""}function _(){return new e}e.prototype=_.prototype={constructor:e,moveTo:function(t,i){this._+="M"+(this._x0=this._x1=+t)+","+(this._y0=this._y1=+i)},closePath:function(){null!==this._x1&&(this._x1=this._x0,this._y1=this._y0,this._+="Z")},lineTo:function(t,i){this._+="L"+(this._x1=+t)+","+(this._y1=+i)},quadraticCurveTo:function(t,i,s,h){this._+="Q"+ +t+","+ +i+","+(this._x1=+s)+","+(this._y1=+h)},bezierCurveTo:function(t,i,s,h,e,_){this._+="C"+ +t+","+ +i+","+ +s+","+ +h+","+(this._x1=+e)+","+(this._y1=+_)},arcTo:function(t,s,h,e,_){t=+t,s=+s,h=+h,e=+e,_=+_;var n=this._x1,o=this._y1,r=h-t,a=e-s,u=n-t,f=o-s,c=u*u+f*f;if(_<0)throw new Error("negative radius: "+_);if(null===this._x1)this._+="M"+(this._x1=t)+","+(this._y1=s);else if(c>1e-6)if(Math.abs(f*r-a*u)>1e-6&&_){var x=h-n,y=e-o,M=r*r+a*a,l=x*x+y*y,d=Math.sqrt(M),p=Math.sqrt(c),v=_*Math.tan((i-Math.acos((M+c-l)/(2*d*p)))/2),b=v/p,w=v/d;Math.abs(b-1)>1e-6&&(this._+="L"+(t+b*u)+","+(s+b*f)),this._+="A"+_+","+_+",0,0,"+ +(f*x>u*y)+","+(this._x1=t+w*r)+","+(this._y1=s+w*a)}else this._+="L"+(this._x1=t)+","+(this._y1=s);else;},arc:function(t,e,_,n,o,r){t=+t,e=+e,r=!!r;var a=(_=+_)*Math.cos(n),u=_*Math.sin(n),f=t+a,c=e+u,x=1^r,y=r?n-o:o-n;if(_<0)throw new Error("negative radius: "+_);null===this._x1?this._+="M"+f+","+c:(Math.abs(this._x1-f)>1e-6||Math.abs(this._y1-c)>1e-6)&&(this._+="L"+f+","+c),_&&(y<0&&(y=y%s+s),y>h?this._+="A"+_+","+_+",0,1,"+x+","+(t-a)+","+(e-u)+"A"+_+","+_+",0,1,"+x+","+(this._x1=f)+","+(this._y1=c):y>1e-6&&(this._+="A"+_+","+_+",0,"+ +(y>=i)+","+x+","+(this._x1=t+_*Math.cos(o))+","+(this._y1=e+_*Math.sin(o))))},rect:function(t,i,s,h){this._+="M"+(this._x0=this._x1=+t)+","+(this._y0=this._y1=+i)+"h"+ +s+"v"+ +h+"h"+-s+"Z"},toString:function(){return this._}},t.path=_,Object.defineProperty(t,"__esModule",{value:!0})});

lisp/emacs-application-framework/app/mermaid/node_modules/d3-path/package.json

@@ -0,0 +1,47 @@
+{
+  "name": "d3-path",
+  "version": "1.0.9",
+  "description": "Serialize Canvas path commands to SVG.",
+  "keywords": [
+    "d3",
+    "d3-module",
+    "canvas",
+    "path",
+    "svg",
+    "graphics",
+    "CanvasRenderingContext2D",
+    "CanvasPathMethods",
+    "Path2D"
+  ],
+  "homepage": "https://d3js.org/d3-path/",
+  "license": "BSD-3-Clause",
+  "author": {
+    "name": "Mike Bostock",
+    "url": "http://bost.ocks.org/mike"
+  },
+  "main": "dist/d3-path.js",
+  "unpkg": "dist/d3-path.min.js",
+  "jsdelivr": "dist/d3-path.min.js",
+  "module": "src/index.js",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/d3/d3-path.git"
+  },
+  "files": [
+    "dist/**/*.js",
+    "src/**/*.js"
+  ],
+  "scripts": {
+    "pretest": "rollup -c",
+    "test": "tape 'test/**/*-test.js' && eslint src test",
+    "prepublishOnly": "rm -rf dist && yarn test",
+    "postpublish": "git push && git push --tags && cd ../d3.github.com && git pull && cp ../${npm_package_name}/dist/${npm_package_name}.js ${npm_package_name}.v${npm_package_version%%.*}.js && cp ../${npm_package_name}/dist/${npm_package_name}.min.js ${npm_package_name}.v${npm_package_version%%.*}.min.js && git add ${npm_package_name}.v${npm_package_version%%.*}.js ${npm_package_name}.v${npm_package_version%%.*}.min.js && git commit -m \"${npm_package_name} ${npm_package_version}\" && git push && cd - && zip -j dist/${npm_package_name}.zip -- LICENSE README.md dist/${npm_package_name}.js dist/${npm_package_name}.min.js"
+  },
+  "sideEffects": false,
+  "devDependencies": {
+    "eslint": "6",
+    "rollup": "1",
+    "rollup-plugin-terser": "5",
+    "tape": "4"
+  }
+}

lisp/emacs-application-framework/app/mermaid/node_modules/d3-path/src/index.js

@@ -0,0 +1 @@
+export {default as path} from "./path.js";

lisp/emacs-application-framework/app/mermaid/node_modules/d3-path/src/path.js

@@ -0,0 +1,130 @@
+var pi = Math.PI,
+    tau = 2 * pi,
+    epsilon = 1e-6,
+    tauEpsilon = tau - epsilon;
+
+function Path() {
+  this._x0 = this._y0 = // start of current subpath
+  this._x1 = this._y1 = null; // end of current subpath
+  this._ = "";
+}
+
+function path() {
+  return new Path;
+}
+
+Path.prototype = path.prototype = {
+  constructor: Path,
+  moveTo: function(x, y) {
+    this._ += "M" + (this._x0 = this._x1 = +x) + "," + (this._y0 = this._y1 = +y);
+  },
+  closePath: function() {
+    if (this._x1 !== null) {
+      this._x1 = this._x0, this._y1 = this._y0;
+      this._ += "Z";
+    }
+  },
+  lineTo: function(x, y) {
+    this._ += "L" + (this._x1 = +x) + "," + (this._y1 = +y);
+  },
+  quadraticCurveTo: function(x1, y1, x, y) {
+    this._ += "Q" + (+x1) + "," + (+y1) + "," + (this._x1 = +x) + "," + (this._y1 = +y);
+  },
+  bezierCurveTo: function(x1, y1, x2, y2, x, y) {
+    this._ += "C" + (+x1) + "," + (+y1) + "," + (+x2) + "," + (+y2) + "," + (this._x1 = +x) + "," + (this._y1 = +y);
+  },
+  arcTo: function(x1, y1, x2, y2, r) {
+    x1 = +x1, y1 = +y1, x2 = +x2, y2 = +y2, r = +r;
+    var x0 = this._x1,
+        y0 = this._y1,
+        x21 = x2 - x1,
+        y21 = y2 - y1,
+        x01 = x0 - x1,
+        y01 = y0 - y1,
+        l01_2 = x01 * x01 + y01 * y01;
+
+    // Is the radius negative? Error.
+    if (r < 0) throw new Error("negative radius: " + r);
+
+    // Is this path empty? Move to (x1,y1).
+    if (this._x1 === null) {
+      this._ += "M" + (this._x1 = x1) + "," + (this._y1 = y1);
+    }
+
+    // Or, is (x1,y1) coincident with (x0,y0)? Do nothing.
+    else if (!(l01_2 > epsilon));
+
+    // Or, are (x0,y0), (x1,y1) and (x2,y2) collinear?
+    // Equivalently, is (x1,y1) coincident with (x2,y2)?
+    // Or, is the radius zero? Line to (x1,y1).
+    else if (!(Math.abs(y01 * x21 - y21 * x01) > epsilon) || !r) {
+      this._ += "L" + (this._x1 = x1) + "," + (this._y1 = y1);
+    }
+
+    // Otherwise, draw an arc!
+    else {
+      var x20 = x2 - x0,
+          y20 = y2 - y0,
+          l21_2 = x21 * x21 + y21 * y21,
+          l20_2 = x20 * x20 + y20 * y20,
+          l21 = Math.sqrt(l21_2),
+          l01 = Math.sqrt(l01_2),
+          l = r * Math.tan((pi - Math.acos((l21_2 + l01_2 - l20_2) / (2 * l21 * l01))) / 2),
+          t01 = l / l01,
+          t21 = l / l21;
+
+      // If the start tangent is not coincident with (x0,y0), line to.
+      if (Math.abs(t01 - 1) > epsilon) {
+        this._ += "L" + (x1 + t01 * x01) + "," + (y1 + t01 * y01);
+      }
+
+      this._ += "A" + r + "," + r + ",0,0," + (+(y01 * x20 > x01 * y20)) + "," + (this._x1 = x1 + t21 * x21) + "," + (this._y1 = y1 + t21 * y21);
+    }
+  },
+  arc: function(x, y, r, a0, a1, ccw) {
+    x = +x, y = +y, r = +r, ccw = !!ccw;
+    var dx = r * Math.cos(a0),
+        dy = r * Math.sin(a0),
+        x0 = x + dx,
+        y0 = y + dy,
+        cw = 1 ^ ccw,
+        da = ccw ? a0 - a1 : a1 - a0;
+
+    // Is the radius negative? Error.
+    if (r < 0) throw new Error("negative radius: " + r);
+
+    // Is this path empty? Move to (x0,y0).
+    if (this._x1 === null) {
+      this._ += "M" + x0 + "," + y0;
+    }
+
+    // Or, is (x0,y0) not coincident with the previous point? Line to (x0,y0).
+    else if (Math.abs(this._x1 - x0) > epsilon || Math.abs(this._y1 - y0) > epsilon) {
+      this._ += "L" + x0 + "," + y0;
+    }
+
+    // Is this arc empty? We’re done.
+    if (!r) return;
+
+    // Does the angle go the wrong way? Flip the direction.
+    if (da < 0) da = da % tau + tau;
+
+    // Is this a complete circle? Draw two arcs to complete the circle.
+    if (da > tauEpsilon) {
+      this._ += "A" + r + "," + r + ",0,1," + cw + "," + (x - dx) + "," + (y - dy) + "A" + r + "," + r + ",0,1," + cw + "," + (this._x1 = x0) + "," + (this._y1 = y0);
+    }
+
+    // Is this arc non-empty? Draw an arc!
+    else if (da > epsilon) {
+      this._ += "A" + r + "," + r + ",0," + (+(da >= pi)) + "," + cw + "," + (this._x1 = x + r * Math.cos(a1)) + "," + (this._y1 = y + r * Math.sin(a1));
+    }
+  },
+  rect: function(x, y, w, h) {
+    this._ += "M" + (this._x0 = this._x1 = +x) + "," + (this._y0 = this._y1 = +y) + "h" + (+w) + "v" + (+h) + "h" + (-w) + "Z";
+  },
+  toString: function() {
+    return this._;
+  }
+};
+
+export default path;