diff --git a/src/core/calc.test.ts b/src/core/calc.test.ts
index 97e1ed3..05c892c 100644
--- a/src/core/calc.test.ts
+++ b/src/core/calc.test.ts
@@ -1,5 +1,5 @@
 import calc from './calc';
-import { BitwiseOperationExpression, NumericOperand, ExpressionOperand } from '../expression/expression';
+import { BitwiseOperationExpression, ScalarOperand, ExpressionOperand } from '../expression/expression';
 import exp from 'constants';
 
 describe("calc", () => {
@@ -18,9 +18,9 @@ describe("calc", () => {
         var result = calc.calcExpression(new BitwiseOperationExpression(
             "1|2&3",
             [
-                new NumericOperand(1),
-                new ExpressionOperand("|2", new NumericOperand(2), "|"),
-                new ExpressionOperand("&3", new NumericOperand(3), "&"),
+                new ScalarOperand(1),
+                new ExpressionOperand("|2", new ScalarOperand(2), "|"),
+                new ExpressionOperand("&3", new ScalarOperand(3), "&"),
             ]
         ));
         
diff --git a/src/expression/ExpressionOperand.test.ts b/src/expression/ExpressionOperand.test.ts
index 695c41c..8346c91 100644
--- a/src/expression/ExpressionOperand.test.ts
+++ b/src/expression/ExpressionOperand.test.ts
@@ -1,8 +1,8 @@
-import NumericOperand from "./NumericOperand";
+import ScalarOperand from "./ScalarOperand";
 import ExpressionOperand from './ExpressionOperand';
 
 it('can apply ~ operand', () => {
-    var op = new NumericOperand(10, 'dec');
+    var op = new ScalarOperand(10, 'dec');
     var expr = new ExpressionOperand("~10", op, "~");
     var result = expr.evaluate();
     expect(result.value).toBe(-11);
@@ -10,8 +10,8 @@ it('can apply ~ operand', () => {
 });
 
 it('can apply & operand', () => {
-    var op1 = new NumericOperand(3, 'dec');
-    var op2 = new NumericOperand(4, 'dec');
+    var op1 = new ScalarOperand(3, 'dec');
+    var op2 = new ScalarOperand(4, 'dec');
     var expr = new ExpressionOperand("|3", op1, "|");
     var result = expr.evaluate(op2);
     expect(result.value).toBe(7);
diff --git a/src/expression/ExpressionOperand.ts b/src/expression/ExpressionOperand.ts
index 63e8e1c..0fb250b 100644
--- a/src/expression/ExpressionOperand.ts
+++ b/src/expression/ExpressionOperand.ts
@@ -1,4 +1,4 @@
-import NumericOperand from './NumericOperand';
+import ScalarOperand from './ScalarOperand';
 import { ExpressionInputItem } from './expression-interfaces';
 
 export default class ExpressionOperand implements ExpressionInputItem {
@@ -18,7 +18,7 @@ export default class ExpressionOperand implements ExpressionInputItem {
         this.isNotExpression = this.sign === '~';
     }
         
-    evaluate(operand?: NumericOperand) : NumericOperand {
+    evaluate(operand?: ScalarOperand) : ScalarOperand {
         if (operand instanceof ExpressionOperand) {
             throw new Error('value shouldnt be expression'); 
         }
@@ -35,10 +35,10 @@ export default class ExpressionOperand implements ExpressionInputItem {
             str = operand.value + this.sign + evaluatedOperand.value;
         }
 
-        return NumericOperand.create(eval(str), evaluatedOperand.base);
+        return ScalarOperand.create(eval(str), evaluatedOperand.base);
     }
 
-    getUnderlyingOperand() : NumericOperand {
+    getUnderlyingOperand() : ScalarOperand {
         return this.operand.getUnderlyingOperand();
     }
 
diff --git a/src/expression/ExpressionParser.test.ts b/src/expression/ExpressionParser.test.ts
new file mode 100644
index 0000000..da36764
--- /dev/null
+++ b/src/expression/ExpressionParser.test.ts
@@ -0,0 +1,68 @@
+import { NumericLiteral } from "typescript";
+import ExpressionOperand from "./ExpressionOperand";
+import { ScalarOperand } from "./expression";
+import { ExpressionInputItem } from "./expression-interfaces";
+
+const NUMBER_REGEX = /./;
+
+class ExpressionParser
+{
+    input: string;
+    pos: number;
+    
+    constructor(input: string) {
+        this.input = input;
+        this.pos = 0;
+    }
+
+    tryParse () : ExpressionInputItem[] | null {
+        return null;
+    } 
+
+    parse() : ExpressionInputItem[] {
+        const s = this.input;
+        const p = this.pos;
+        const items : ExpressionInputItem[] = [];
+        
+        while(p < s.length) {
+            
+           
+           
+        }
+
+        return items;
+    }
+
+    parseSingle(): ExpressionInputItem {
+        const s = this.input;
+        const p = this.pos;
+
+        const ch = s[p];
+
+        if(ch == '~')
+        {
+            this.move(1); 
+            const inner = this.parseSingle()
+            return new ExpressionOperand("~" + inner, inner, "~");
+        }
+
+        const ss = s.substring(p);
+        const scalar = ScalarOperand.tryParse(ss);
+
+        if(scalar == null)
+            throw new Error(`Expected scalar value at pos ${p}: ${ss}`);
+
+        return {} as ExpressionInputItem;
+    }
+
+    move(step : number) {
+        this.pos += step;
+    }
+
+    
+}
+
+it("parses simple expression", () => {
+    const input = "1+1";
+    
+})
\ No newline at end of file
diff --git a/src/expression/ListOfNumbersExpression.test.ts b/src/expression/ListOfNumbersExpression.test.ts
index a415baf..546e297 100644
--- a/src/expression/ListOfNumbersExpression.test.ts
+++ b/src/expression/ListOfNumbersExpression.test.ts
@@ -1,7 +1,7 @@
-import NumericOperand from "./NumericOperand";
+import ScalarOperand from "./ScalarOperand";
 import ListOfNumbersExpression from "./ListOfNumbersExpression";
 
 it('calculates max bits length', () => {
-    var expr = new ListOfNumbersExpression("10 0xabef 0b01010", [NumericOperand.parse("10"), NumericOperand.parse("0xabef"), NumericOperand.parse("0b01010")])
+    var expr = new ListOfNumbersExpression("10 0xabef 0b01010", [ScalarOperand.parse("10"), ScalarOperand.parse("0xabef"), ScalarOperand.parse("0b01010")])
     expect(expr.maxBitsLength).toBe(16);
 });
diff --git a/src/expression/ListOfNumbersExpression.ts b/src/expression/ListOfNumbersExpression.ts
index f28a086..775cf75 100644
--- a/src/expression/ListOfNumbersExpression.ts
+++ b/src/expression/ListOfNumbersExpression.ts
@@ -1,12 +1,12 @@
-import NumericOperand from "./NumericOperand";
+import ScalarOperand from "./ScalarOperand";
 import { ExpressionInput, ExpressionInputItem } from "./expression-interfaces";
 
 export default class ListOfNumbersExpression implements ExpressionInput {
-    numbers: NumericOperand[];
+    numbers: ScalarOperand[];
     expressionString: string;
     maxBitsLength: number;
 
-    constructor(expressionString: string, numbers: NumericOperand[]) {
+    constructor(expressionString: string, numbers: ScalarOperand[]) {
         this.expressionString = expressionString;
         this.numbers = numbers;
         this.maxBitsLength = numbers.map(n => n.lengthInBits).reduce((n , c) => n >= c ? n : c, 0);
diff --git a/src/expression/NumericOperand.test.ts b/src/expression/NumericOperand.test.ts
deleted file mode 100644
index 22b46fa..0000000
--- a/src/expression/NumericOperand.test.ts
+++ /dev/null
@@ -1,26 +0,0 @@
-import NumericOperand, { INT_MAX_VALUE } from './NumericOperand';
-
-it('parsed from string', () => {
-    var op = NumericOperand.parse('123');
-    expect(op.base).toBe('dec');
-    expect(op.value).toBe(123);
-});
-
-it('can get other kind', () => {
-    var op = new NumericOperand(10, 'dec');
-    expect(op.getOtherBase('hex')).toBe('dec');
-    expect(op.getOtherBase('bin')).toBe('hex');    
-});
-
-it('negtive value binary string', () => {
-    expect(NumericOperand.toBaseString(-1, 'bin')).toBe('11111111111111111111111111111111');
-});
-
-it('64 bit operand binary string', () => {
-    expect(NumericOperand.toBaseString(68719476735, 'bin')).toBe('111111111111111111111111111111111111');
-});
-
-it('throws on negative 64 bit numbers', () => {
-    var bigN = -(INT_MAX_VALUE+1);
-    expect(() => new NumericOperand(bigN)).toThrowError("BitwiseCmd currently doesn't support 64 bit negative numbers such as " + bigN);
-})
\ No newline at end of file
diff --git a/src/expression/ScalarOperand.test.ts b/src/expression/ScalarOperand.test.ts
new file mode 100644
index 0000000..154befe
--- /dev/null
+++ b/src/expression/ScalarOperand.test.ts
@@ -0,0 +1,26 @@
+import ScalarOperand, { INT_MAX_VALUE } from './ScalarOperand';
+
+it('parsed from string', () => {
+    var op = ScalarOperand.parse('123');
+    expect(op.base).toBe('dec');
+    expect(op.value).toBe(123);
+});
+
+it('can get other kind', () => {
+    var op = new ScalarOperand(10, 'dec');
+    expect(op.getOtherBase('hex')).toBe('dec');
+    expect(op.getOtherBase('bin')).toBe('hex');    
+});
+
+it('negtive value binary string', () => {
+    expect(ScalarOperand.toBaseString(-1, 'bin')).toBe('11111111111111111111111111111111');
+});
+
+it('64 bit operand binary string', () => {
+    expect(ScalarOperand.toBaseString(68719476735, 'bin')).toBe('111111111111111111111111111111111111');
+});
+
+it('throws on negative 64 bit numbers', () => {
+    var bigN = -(INT_MAX_VALUE+1);
+    expect(() => new ScalarOperand(bigN)).toThrowError("BitwiseCmd currently doesn't support 64 bit negative numbers such as " + bigN);
+})
\ No newline at end of file
diff --git a/src/expression/NumericOperand.ts b/src/expression/ScalarOperand.ts
similarity index 79%
rename from src/expression/NumericOperand.ts
rename to src/expression/ScalarOperand.ts
index 3faf28e..5761575 100644
--- a/src/expression/NumericOperand.ts
+++ b/src/expression/ScalarOperand.ts
@@ -7,8 +7,8 @@ const INT_MAX_VALUE = 2147483647;
 
 export {INT_MAX_VALUE};
 
-// Represents numeric value
-export default class NumericOperand implements ExpressionInputItem {
+// Represents scalar numeric value
+export default class ScalarOperand implements ExpressionInputItem {
     id: number;
     value: number;
     base: NumberBase;
@@ -19,10 +19,10 @@ export default class NumericOperand implements ExpressionInputItem {
         this.id = globalId++;
         this.value = value;
         this.base = base || "dec";
-        this.lengthInBits = NumericOperand.getBitLength(this.value);
+        this.lengthInBits = ScalarOperand.getBitLength(this.value);
         this.isExpression = false;
 
-        if(value < 0 && !NumericOperand.is32Bit(value))
+        if(value < 0 && !ScalarOperand.is32Bit(value))
             throw new Error("BitwiseCmd currently doesn't support 64 bit negative numbers such as " + value);
     }
             
@@ -44,7 +44,7 @@ export default class NumericOperand implements ExpressionInputItem {
     };
 
     toString(base?: NumberBase) : string {
-        return NumericOperand.toBaseString(this.value, base || this.base);
+        return ScalarOperand.toBaseString(this.value, base || this.base);
     }
 
     toOtherKindString() : string {
@@ -65,14 +65,14 @@ export default class NumericOperand implements ExpressionInputItem {
 
     setValue(value : number) {
         this.value = value;
-        this.lengthInBits = NumericOperand.getBitLength(value);
+        this.lengthInBits = ScalarOperand.getBitLength(value);
     }
 
-    evaluate() : NumericOperand {
+    evaluate() : ScalarOperand {
         return this;
     }
 
-    getUnderlyingOperand() : NumericOperand  {
+    getUnderlyingOperand() : ScalarOperand  {
         return this
     }
         
@@ -89,12 +89,12 @@ export default class NumericOperand implements ExpressionInputItem {
     };
 
     static create(value : number, base? : NumberBase) {
-        return new NumericOperand(value, base || "dec");
+        return new ScalarOperand(value, base || "dec");
     };
 
-    static parse(input: string) : NumericOperand {
+    static parse(input: string) : ScalarOperand {
                     
-        var parsed = NumericOperand.tryParse(input);
+        var parsed = ScalarOperand.tryParse(input);
 
         if(parsed == null) {
             throw new Error(input + " is not a valid number");
@@ -103,7 +103,7 @@ export default class NumericOperand implements ExpressionInputItem {
         return parsed;
     }
 
-    static tryParse(input: string) : NumericOperand | null {
+    static tryParse(input: string) : ScalarOperand | null {
                     
         var parsed = numberParser.parse(input);
 
@@ -111,7 +111,7 @@ export default class NumericOperand implements ExpressionInputItem {
             return null;
         }
 
-        return new NumericOperand(parsed.value, parsed.base);
+        return new ScalarOperand(parsed.value, parsed.base);
     }
 
     static toBaseString(value : number, base : NumberBase) : string {
@@ -122,7 +122,7 @@ export default class NumericOperand implements ExpressionInputItem {
             case 'bin':
                 // >>> 0 is used to get an actual bit representation of the negative numbers
                 // https://stackoverflow.com/questions/5747123/strange-javascript-operator-expr-0
-                const is32Bit = NumericOperand.is32Bit(value);
+                const is32Bit = ScalarOperand.is32Bit(value);
                 return (is32Bit && value < 0 ? (value >>> 0) : value).toString(2);
             case 'dec':
                 return value.toString(10);
diff --git a/src/expression/components/BitwiseExpressionModel.ts b/src/expression/components/BitwiseExpressionModel.ts
index ee1734f..31f0a6e 100644
--- a/src/expression/components/BitwiseExpressionModel.ts
+++ b/src/expression/components/BitwiseExpressionModel.ts
@@ -1,4 +1,4 @@
-import { NumericOperand, ListOfNumbersExpression, BitwiseOperationExpression, ExpressionOperand } from '../expression';
+import { ScalarOperand, ListOfNumbersExpression, BitwiseOperationExpression, ExpressionOperand } from '../expression';
 import { ExpressionInputItem, ExpressionInput } from '../expression-interfaces';
 
 type Config = {
@@ -41,11 +41,11 @@ export default class BitwiseExpressionViewModel {
             i = 0, len = expr.expressionItems.length,
             ex, m = new BitwiseExpressionViewModel(config);
 
-        var prev : NumericOperand | null = null;
+        var prev : ScalarOperand | null = null;
 
         for (;i<len;i++) {
             ex = expr.expressionItems[i];
-            if(ex instanceof NumericOperand) {
+            if(ex instanceof ScalarOperand) {
                 m.addOperandRow(ex);
                 prev = ex;
                 continue;
@@ -61,11 +61,11 @@ export default class BitwiseExpressionViewModel {
                 prev = notResult;
             }
             else if(eo.isShiftExpression){
-                prev = eo.evaluate(prev as NumericOperand);
+                prev = eo.evaluate(prev as ScalarOperand);
                 m.addShiftExpressionResultRow(eo, prev);
             } else {
 
-                prev = eo.evaluate(prev as NumericOperand);
+                prev = eo.evaluate(prev as ScalarOperand);
                 m.addExpressionOperandRow(eo);
                 m.addExpressionResultRow(prev);
             }
@@ -84,7 +84,7 @@ export default class BitwiseExpressionViewModel {
         return m;
     };
 
-    addOperandRow(operand: NumericOperand) {
+    addOperandRow(operand: ScalarOperand) {
         this.maxNumberOfBits = Math.max(operand.getLengthInBits(), this.maxNumberOfBits);
         this.items.push({ 
             sign:'', 
@@ -108,7 +108,7 @@ export default class BitwiseExpressionViewModel {
         });
     };
 
-    addShiftExpressionResultRow(expression : ExpressionOperand, resultOperand : NumericOperand) {
+    addShiftExpressionResultRow(expression : ExpressionOperand, resultOperand : ScalarOperand) {
         this.maxNumberOfBits = Math.max(resultOperand.getLengthInBits(), this.maxNumberOfBits);
         this.items.push({
             sign: expression.sign + expression.operand.toString(),
@@ -119,7 +119,7 @@ export default class BitwiseExpressionViewModel {
         });
     };
 
-    addExpressionResultRow(operand : NumericOperand) {
+    addExpressionResultRow(operand : ScalarOperand) {
         this.maxNumberOfBits = Math.max(operand.getLengthInBits(), this.maxNumberOfBits);
         this.items.push({ 
             sign:'=', 
@@ -130,7 +130,7 @@ export default class BitwiseExpressionViewModel {
         });
     };
 
-    getLabel (op: NumericOperand) : string {
+    getLabel (op: ScalarOperand) : string {
         
         if(op.base == 'bin') {
             return op.toString("dec");
diff --git a/src/expression/components/BitwiseOperationExpressionView.tsx b/src/expression/components/BitwiseOperationExpressionView.tsx
index 6b05d45..d0831c6 100644
--- a/src/expression/components/BitwiseOperationExpressionView.tsx
+++ b/src/expression/components/BitwiseOperationExpressionView.tsx
@@ -3,7 +3,7 @@ import formatter from '../../core/formatter';
 import BinaryStringView, { FlipBitEventArg } from '../../core/components/BinaryString';
 import BitwiseExpressionViewModel from './BitwiseExpressionModel';
 import { ExpressionInput, ExpressionInputItem } from '../expression-interfaces';
-import { ExpressionOperand, NumericOperand } from '../expression';
+import { ExpressionOperand, ScalarOperand } from '../expression';
 
 type BitwiseOperationExpressionViewProps = {
     expression: ExpressionInput;
@@ -114,7 +114,7 @@ class ExpressionRow extends React.Component<ExpressionRowProps> {
         return this.props.expressionItem.evaluate().toOtherKindString();
     }
 
-    getLabelString (op: NumericOperand) : string {
+    getLabelString (op: ScalarOperand) : string {
         return op.toString(op.base == 'bin' ? 'dec' : op.base);
     }
 
diff --git a/src/expression/expression-interfaces.ts b/src/expression/expression-interfaces.ts
index 0a470d2..106dba0 100644
--- a/src/expression/expression-interfaces.ts
+++ b/src/expression/expression-interfaces.ts
@@ -1,4 +1,4 @@
-import { NumericOperand } from "./expression";
+import { ScalarOperand } from "./expression";
 
 export interface ExpressionInput
 {
@@ -8,8 +8,8 @@ export interface ExpressionInput
 export interface ExpressionInputItem 
 {
     isExpression: boolean;   
-    getUnderlyingOperand: () => NumericOperand;
-    evaluate(operand? : NumericOperand): NumericOperand;
+    getUnderlyingOperand: () => ScalarOperand;
+    evaluate(operand? : ScalarOperand): ScalarOperand;
 }
 
 export type NumberBase = 'dec' | 'hex' | 'bin';
diff --git a/src/expression/expression.test.ts b/src/expression/expression.test.ts
index 206a58d..c88dc08 100644
--- a/src/expression/expression.test.ts
+++ b/src/expression/expression.test.ts
@@ -1,5 +1,5 @@
 import { OperationCanceledException } from "typescript";
-import { parser, ListOfNumbersExpression, BitwiseOperationExpression, NumericOperand, ExpressionOperand } from "./expression";
+import { parser, ListOfNumbersExpression, BitwiseOperationExpression, ScalarOperand, ExpressionOperand } from "./expression";
 
 describe("expression parser", () => {
 
@@ -37,16 +37,16 @@ describe("expression parser", () => {
         const first = result.expressionItems[0];
         const second = result.expressionItems[1];
 
-        expect(first).toBeInstanceOf(NumericOperand);
+        expect(first).toBeInstanceOf(ScalarOperand);
 
-        expect((first as NumericOperand).value).toBe(1);
+        expect((first as ScalarOperand).value).toBe(1);
 
         expect(second).toBeInstanceOf(ExpressionOperand);
         var secondOp = second as ExpressionOperand;
         expect(secondOp.sign).toBe("^");
 
-        expect(secondOp.operand).toBeInstanceOf(NumericOperand);
-        var childOp = secondOp.operand as NumericOperand;
+        expect(secondOp.operand).toBeInstanceOf(ScalarOperand);
+        var childOp = secondOp.operand as ScalarOperand;
         expect(childOp.value).toBe(2);
     });
 
diff --git a/src/expression/expression.ts b/src/expression/expression.ts
index dc3ceaf..4897697 100644
--- a/src/expression/expression.ts
+++ b/src/expression/expression.ts
@@ -1,10 +1,10 @@
-import NumericOperand from './NumericOperand';
+import ScalarOperand from './ScalarOperand';
 import ExpressionOperand from './ExpressionOperand'
 import ListOfNumbersExpression from './ListOfNumbersExpression';
 import BitwiseOperationExpression from './BitwiseOperationExpression';
 import { ExpressionInput, ExpressionInputItem, NumberBase } from './expression-interfaces';
 
-export { default as NumericOperand } from './NumericOperand';
+export { default as ScalarOperand } from './ScalarOperand';
 export { default as ExpressionOperand } from './ExpressionOperand';
 export { default as ListOfNumbersExpression } from './ListOfNumbersExpression';
 export { default as BitwiseOperationExpression } from './BitwiseOperationExpression';
@@ -46,12 +46,12 @@ class ExpressionParser {
         return null;
     };
     
-    parseOperand (input : string) : NumericOperand {
-        return NumericOperand.parse(input);
+    parseOperand (input : string) : ScalarOperand {
+        return ScalarOperand.parse(input);
     };
 
-    createOperand (number : number, base : NumberBase) : NumericOperand {
-        return NumericOperand.create(number, base);
+    createOperand (number : number, base : NumberBase) : ScalarOperand {
+        return ScalarOperand.create(number, base);
     };
 
     addFactory (factory: IExpressionParserFactory) {
@@ -69,7 +69,7 @@ class ListOfNumbersExpressionFactory implements IExpressionParserFactory
         
         return input.split(' ')
             .filter(p => p.length > 0)
-            .map(p => NumericOperand.tryParse(p))
+            .map(p => ScalarOperand.tryParse(p))
             .filter(n => n == null)
             .length == 0;
     };
@@ -78,7 +78,7 @@ class ListOfNumbersExpressionFactory implements IExpressionParserFactory
         
         const numbers = input.split(' ')
             .filter(p => p.length > 0)
-            .map(m => NumericOperand.parse(m));
+            .map(m => ScalarOperand.parse(m));
 
         return new ListOfNumbersExpression(input, numbers);
     }
@@ -116,16 +116,16 @@ class BitwiseOperationExpressionFactory implements IExpressionParserFactory {
 
         var parsed = null;
         if(num.indexOf('~') == 0) {
-            parsed = new ExpressionOperand(num, NumericOperand.parse(num.substring(1)), '~');
+            parsed = new ExpressionOperand(num, ScalarOperand.parse(num.substring(1)), '~');
         }
         else {
-            parsed = NumericOperand.parse(num);
+            parsed = ScalarOperand.parse(num);
         }
 
         if(sign == null) {
             return parsed as ExpressionOperand;
         } else {
-            return new ExpressionOperand(input, parsed as NumericOperand, sign);
+            return new ExpressionOperand(input, parsed as ScalarOperand, sign);
         }
     };