From d558fae74ec527c7836d380bd8a6c2dcf784eb0c Mon Sep 17 00:00:00 2001
From: Evgeny Metelkin <metelkin@insysbio.com>
Date: Tue, 22 Jun 2021 14:25:01 +0300
Subject: [PATCH] piecewise function

---
 package-lock.json      |  2 +-
 package.json           |  2 +-
 src/cmathml-handler.js | 23 ++++++++++++++++++-----
 test/cases/nodes.json  |  8 ++++++++
 4 files changed, 28 insertions(+), 7 deletions(-)

diff --git a/package-lock.json b/package-lock.json
index edaa304..ea573a7 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "mathjs-mathml",
-  "version": "0.3.0",
+  "version": "0.3.1",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
diff --git a/package.json b/package.json
index 3bfeb5b..11c0646 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "mathjs-mathml",
-  "version": "0.3.0",
+  "version": "0.3.1",
   "description": "Translation of mathjs object to MathML",
   "main": "src/index.js",
   "scripts": {
diff --git a/src/cmathml-handler.js b/src/cmathml-handler.js
index e8a617b..f58df6c 100644
--- a/src/cmathml-handler.js
+++ b/src/cmathml-handler.js
@@ -31,15 +31,28 @@ function cMathMLHandler(_this, { handler, csymbols }){
   } else if (_this.type === 'FunctionNode') {
     let args = _this.args
       .map((arg) => arg.toString({handler, csymbols}));
-    if(_this.fn.name==='cube'){
+    if (_this.fn.name==='cube') {
       return `<apply><power/>${args[0]}<cn>3</cn></apply>`;
-    }else if(_this.fn.name==='square'){
+    } else if(_this.fn.name==='square') {
       return `<apply><power/>${args[0]}<cn>2</cn></apply>`;
-    }else if(_this.fn.name==='log' && _this.args.length===2){
+    } else if(_this.fn.name==='log' && _this.args.length===2) {
       return `<apply><log/><logbase>${args[1]}</logbase>${args[0]}</apply>`;
-    }else if(_this.fn.name==='log2'){
+    } else if(_this.fn.name==='log2') {
       return `<apply><log/><logbase><cn>2</cn></logbase>${args[0]}</apply>`;
-    }else{ // change only function name
+    } else if (_this.fn.name === 'piecewise') {
+      if (args.length === 0) throw new Error('piecewise function must have at least one argument.');
+
+      let hasOtherwise = args.length % 2 == 1; // is odd
+      let otherwiseTag = hasOtherwise ? `<otherwise>${args[args.length - 1]}</otherwise>` : ``;
+
+      let piecesCount = Math.floor(args.length / 2);
+      let piecesTags = [];
+      for (let i = 0; i < piecesCount; i++) {
+        let tag = `<piece>${args[2*i+1]}${args[2*i]}</piece>`;
+        piecesTags.push(tag);
+      }
+      return `<piecewise>${piecesTags.join('')}${otherwiseTag}</piecewise>`;
+    } else { // change only function name
       return `<apply><${dictFunc[_this.fn.name] || _this.fn.name}/>${args.join('')}</apply>`;
     }
   } else if (_this.type === 'OperatorNode') {
diff --git a/test/cases/nodes.json b/test/cases/nodes.json
index 57761d3..46302b6 100644
--- a/test/cases/nodes.json
+++ b/test/cases/nodes.json
@@ -132,5 +132,13 @@
   "not false": {
     "formula": "not false",
     "expected": "<apply><not/><false/></apply>"
+  },
+  "piecewise": {
+    "formula": "123 * piecewise(x > 1, 1, x > 2, 2, 0)",
+    "expected": "<apply><times/><cn>123</cn><piecewise><piece><cn>1</cn><apply><gt/><ci>x</ci><cn>1</cn></apply></piece><piece><cn>2</cn><apply><gt/><ci>x</ci><cn>2</cn></apply></piece><otherwise><cn>0</cn></otherwise></piecewise></apply>"
+  },
+  "piecewise without otherwise": {
+    "formula": "123 * piecewise(x > 1, 1, x > 2, 2)",
+    "expected": "<apply><times/><cn>123</cn><piecewise><piece><cn>1</cn><apply><gt/><ci>x</ci><cn>1</cn></apply></piece><piece><cn>2</cn><apply><gt/><ci>x</ci><cn>2</cn></apply></piece></piecewise></apply>"
   }
 }