Chris Willis

index.js

@@ -1 +1,143 @@
+'use strict';
 
+const readline = require('readline');
+
+
+const rl = readline.createInterface({
+  input: process.stdin,
+  output: process.stdout
+});
+
+const nameTester = (name,index) => {
+  if(variableSpace[index]){
+    return Number(name.value);
+  }else if(index==="true"||index==="false"){
+    return JSON.parse(index)
+
+  }
+}
+
+const nodePlayground = (answer) => {
+  const splitAnswer = answer.trim().replace(/ +(?= )/g,'').split(" ");
+  // we are nice to the user, to nice probably. We trim leadning and trailing
+  // spaces and knock out any silly spaces in between since we are seperating
+  // on a join, interal spacing is important. If they run everything together,
+  // and have no spacing, we will not save the user from this
+  if(splitAnswer.length==3){
+
+    // console.log(JSON.parse(splitAnswer[0]))
+    // console.log(Number(JSON.parse(splitAnswer[0])))
+    // console.log(isNaN(Number(JSON.parse(splitAnswer[0]))))
+
+
+    // if we split the string and there are 3 bits, some kind of math or logic
+    // was done, test for what kinda logic we need to do.
+    const firstTerm = isNaN(Number(splitAnswer[0]))? nameTester(variableSpace[splitAnswer[0]],splitAnswer[0]) : Number(splitAnswer[0]);
+    const secondTerm = isNaN(Number(splitAnswer[2]))? nameTester(variableSpace[splitAnswer[2]],splitAnswer[2]) : Number(splitAnswer[2]);
+    // esoteric bit of logic. Basically, was a number written?
+    // if so, proceed. If not check to see if it is a variable we know about
+    // and replace it inline, if not logic below throws refference error. 
+
+    // can't test for falsy cause 0 is a valid entry
+    if(firstTerm===undefined){
+      return `ReferenceError: ${splitAnswer[0]} is not defined`
+    }else if(secondTerm===undefined){
+      return `ReferenceError: ${splitAnswer[2]} is not defined`
+
+    }
+    // test for operand and perform operation, prob a smarter way to do this
+    // but went with brute force...and it hurts!
+    if(splitAnswer[1]=='+'){
+      return `${firstTerm}${splitAnswer[1]}${secondTerm}=${firstTerm+secondTerm}` 
+    }
+    else if(splitAnswer[1]=='-'){
+      return `${firstTerm}${splitAnswer[1]}${secondTerm}=${firstTerm-secondTerm}` 
+    }
+    else if(splitAnswer[1]=='*'){
+      return `${firstTerm}${splitAnswer[1]}${secondTerm}=${firstTerm*secondTerm}`      
+    }
+    else if(splitAnswer[1]=='/'){
+      return `${firstTerm}${splitAnswer[1]}${secondTerm}=${firstTerm/secondTerm}`       
+    }
+    else if(splitAnswer[1]=='<'){
+      return `${firstTerm}${splitAnswer[1]}${secondTerm}=${firstTerm<secondTerm}`       
+    }
+    else if(splitAnswer[1]=='>'){
+      return `${firstTerm}${splitAnswer[1]}${secondTerm}=${firstTerm>secondTerm}`       
+    }
+    else if(splitAnswer[1]=='==='){
+      return `${firstTerm}${splitAnswer[1]}${secondTerm}=${firstTerm===secondTerm}`       
+    }
+    else if(splitAnswer[1]=='!=='){
+      return `${firstTerm}${splitAnswer[1]}${secondTerm}=${firstTerm!==secondTerm}`       
+    }
+    else if(splitAnswer[1]=='='){
+      // fancy bit for reasigning varibles. if it exists in variable namespace
+      // see if it isn't a const, if it is, throw error
+      if(variableSpace[splitAnswer[0]] && variableSpace[splitAnswer[0]].type == 'const'){
+        return "TypeError: Assignment to constant variable"
+      }
+      // if not const, reasign value, keep existing type
+      variableSpace[splitAnswer[0]] = {value: splitAnswer[2],type:variableSpace[splitAnswer[0]].type}
+      return splitAnswer[0] +" => "+ variableSpace[splitAnswer[0]].value;
+    }
+    else{
+      // if we have 3 fields and one isn't listed about, its not something
+      // we are going to handel
+      return "Syntax Error"
+    }
+  }else if (splitAnswer.length==4){
+    // len 4 implies variable creation
+    const varType = splitAnswer[0];
+    const varName = splitAnswer[1];
+    const varValue = splitAnswer[3];
+
+    // if it isn't a recognized type, blow up
+    if (!(varType=="const" || varType == "let" || varType == "var") ){
+      return "SyntaxError: Unexpected identifier, " + varType
+    }
+
+    // if variable already exists in namespace, blow up
+    if(variableSpace[varName]){
+      return `SyntaxError: Identifier, ${varName}, has already been declared`
+    } 
+
+    if(!isNaN(varName)){
+      return `SyntaxError: Unexpected number, ${varName}, invalid variable name`
+    }
+
+    // finally, if it doesn't exist and is the correct variable type
+    // create namespace object with name as key to data object, 
+    // data object tells what kind of datatype and its value
+    variableSpace[splitAnswer[1]] = {value:splitAnswer[3],type:splitAnswer[0]}
+    return varName+ " => " + varValue
+  }else if(splitAnswer.length==1){
+    // look at namespace and return the value
+    if(variableSpace[splitAnswer[0]]){
+      return variableSpace[splitAnswer[0]].value
+    } 
+
+    // blow up if you don't find it
+    return `ReferenceError: ${splitAnswer[0]} is not defined` 
+  }else{
+
+    return "Syntax Error"
+  }
+}
+
+
+const getPrompt = () => {
+
+  // recursive call, we are here till end of time
+  rl.question('Node playground, enter values  ', (answer) => {
+    console.log(nodePlayground(answer));
+    getPrompt();
+  })
+  }
+
+
+// container of all created varibles
+const variableSpace = {};
+
+
+getPrompt();