From fa40223ec40b58f0badd5f78a61a5103ca52dcdb Mon Sep 17 00:00:00 2001
From: Ghassan Nasr <ghassan.nasr@gmail.com>
Date: Tue, 30 Jun 2020 23:42:44 -0400
Subject: [PATCH] completed assignment and corrected one test case

---
 assets/js/footer-functions.js |  2 +-
 assets/js/numbers.js          | 91 ++++++++++++++++++++++++++++++++++-
 2 files changed, 90 insertions(+), 3 deletions(-)

diff --git a/assets/js/footer-functions.js b/assets/js/footer-functions.js
index 3587073..3b78ea2 100644
--- a/assets/js/footer-functions.js
+++ b/assets/js/footer-functions.js
@@ -45,7 +45,7 @@ function additionAndSubtractionTest() {
 
 
 function additionAndMultiplicationTest() {
-    testCompute(0, "1+1*2");
+    testCompute(3, "1+1*2");
     testCompute(16, "10+6*1");
     testCompute(34, "10+2*12");
 }
diff --git a/assets/js/numbers.js b/assets/js/numbers.js
index 5a925a6..b02fd1d 100644
--- a/assets/js/numbers.js
+++ b/assets/js/numbers.js
@@ -1,3 +1,90 @@
 function compute(expression) {
-    // TODO - write method definition here
-}
\ No newline at end of file
+  let exp = new Expression(expression);
+  
+  exp.doHighPrecedenceOperations();
+  exp.doLowPrecedenceOperations();
+
+  return parseFloat(exp.expArr[0]);
+}
+
+
+class Expression {
+  constructor(expString) {
+    this.expArr = this.parseStringExpressionToArray(expString);
+  }
+
+  parseStringExpressionToArray(expString) {
+    
+    //will create two arrays, one of all the operands
+    //and another of all the operators, then merge them
+    
+    //create a copy of string expression first
+    let temp = expString;
+
+    //replace all clusters of digits with underscores
+    expString = expString.replace(/[0-9]+/g, "_");
+
+    //create an array of the operators only by splitting on the underscore
+    //and filtering out the empty values in the resulting array
+    let operators = expString.split("_").filter(function(str){return str != ""});
+
+    //create an array of all the strings of numbers that were parsed out
+    let operands = temp.split(/[^0-9\.]+/);
+
+    //now ready to merge the operands and operators in a new array "result"
+    let result = [];
+
+    for(let i = 0; i < operands.length; i++){
+      //for every operand, push and operator, except when the
+      //last operand is reached
+      result.push(operands[i]);
+      if (i < operators.length) result.push(operators[i]);
+    }
+    
+    return result;
+  }
+
+  doHighPrecedenceOperations() {
+    let currIndex = 0;
+    while(currIndex < this.expArr.length-1) {
+      let currValue = this.expArr[currIndex];
+      if(currValue == "*" || currValue == "/") {
+        let result;
+        let operand1 = parseFloat(this.expArr[currIndex-1], 10);
+        let operand2 = parseFloat(this.expArr[currIndex+1], 10);
+        if(currValue == "*")
+          result = operand1 * operand2;
+        else
+          result = operand1 / operand2;
+
+        //insert the result at the first operand's position and remove three elements
+        result = result.toString();
+        this.expArr.splice(currIndex-1, 3, result);
+      }
+      else
+        currIndex++;
+    }
+  }
+
+  doLowPrecedenceOperations() {
+    let currIndex = 0;
+    while(currIndex < this.expArr.length-1) {
+      let currValue = this.expArr[currIndex];
+      if(currValue == "+" || currValue == "-") {
+        let result;
+        let operand1 = parseFloat(this.expArr[currIndex-1], 10);
+        let operand2 = parseFloat(this.expArr[currIndex+1], 10);
+        if(currValue == "-")
+          result = operand1 - operand2;
+        else
+          result = operand1 + operand2;
+
+        //insert the result at the first operand's position and remove three elements
+        result = result.toString();
+        this.expArr.splice(currIndex-1, 3, result);
+      }
+      else
+        currIndex++;
+    }
+  }
+}