diff --git a/src/parser/source-token-reader/index.test.ts b/src/parser/source-token-reader/index.test.ts
new file mode 100644
index 0000000..7e222fd
--- /dev/null
+++ b/src/parser/source-token-reader/index.test.ts
@@ -0,0 +1,76 @@
+import Lexer from "../../lexer";
+import SourceTokenReader from "./";
+
+const createReader = (input: string) => {
+  const lexer = new Lexer(input);
+
+  return new SourceTokenReader(lexer);
+};
+
+describe("read()", () => {
+  it("read a token", () => {
+    const input = "42";
+    const reader = createReader(input);
+    const expected = {
+      type: "number literal",
+      value: "42",
+      range: {
+        begin: { col: 0, row: 0 },
+        end: { col: 1, row: 0 },
+      },
+    };
+
+    expect(reader.read()).toEqual(expected);
+  });
+
+  it("read the end token if nothing to read", () => {
+    const input = "";
+    const reader = createReader(input);
+    const expected = {
+      type: "end",
+      value: "$end",
+      range: {
+        begin: { col: 0, row: 0 },
+        end: { col: 0, row: 0 },
+      },
+    };
+
+    expect(reader.read()).toEqual(expected);
+  });
+});
+
+describe("advance()", () => {
+  it("advance to next token", () => {
+    const input = "42 99";
+    const reader = createReader(input);
+    const expected = {
+      type: "number literal",
+      value: "99",
+      range: {
+        begin: { col: 3, row: 0 },
+        end: { col: 4, row: 0 },
+      },
+    };
+
+    reader.advance();
+    expect(reader.read()).toEqual(expected);
+  });
+});
+
+describe("isEnd()", () => {
+  it("return true if end", () => {
+    const input = "";
+    const reader = createReader(input);
+    const expected = true;
+
+    expect(reader.isEnd()).toEqual(expected);
+  });
+
+  it("return false if not end", () => {
+    const input = "42";
+    const reader = createReader(input);
+    const expected = false;
+
+    expect(reader.isEnd()).toEqual(expected);
+  });
+});
diff --git a/src/parser/source-token-reader/index.ts b/src/parser/source-token-reader/index.ts
new file mode 100644
index 0000000..341117b
--- /dev/null
+++ b/src/parser/source-token-reader/index.ts
@@ -0,0 +1,24 @@
+import Lexer from "../../lexer";
+import type { SourceToken } from "../../lexer";
+
+export default class SourceTokenReader {
+  private readonly lexer: Lexer;
+  private token: SourceToken;
+
+  constructor(lexer: Lexer) {
+    this.lexer = lexer;
+    this.token = lexer.getSourceToken();
+  }
+
+  read(): SourceToken {
+    return this.token;
+  }
+
+  advance(): void {
+    this.token = this.lexer.getSourceToken();
+  }
+
+  isEnd(): boolean {
+    return this.token.type === "end";
+  }
+}
diff --git a/src/parser/syntax-node/base/index.ts b/src/parser/syntax-node/base/index.ts
new file mode 100644
index 0000000..68e77c5
--- /dev/null
+++ b/src/parser/syntax-node/base/index.ts
@@ -0,0 +1,25 @@
+import type Position from "../../../util/position";
+
+export interface SyntaxNodeBase<T extends string = string, F extends {} = {}> {
+  type: T,
+  range: {
+    begin: Position,
+    end: Position,
+  },
+  fields: F,
+};
+
+export function createNodeCreator<N extends SyntaxNodeBase>(type: N["type"]) {
+  function createNode(fields: N["fields"], rangeBegin: Position, rangeEnd: Position) {
+    const range = {
+      begin: rangeBegin,
+      end: rangeEnd,
+    };
+
+    return { type, range, fields };
+  };
+
+  return createNode;
+};
+
+export type CreateNode<N extends SyntaxNodeBase> = (fields: N["fields"], rangeBegin: Position, rangeEnd: Position) => N;
diff --git a/src/parser/syntax-node/expression/index.test.ts b/src/parser/syntax-node/expression/index.test.ts
new file mode 100644
index 0000000..3f40b1c
--- /dev/null
+++ b/src/parser/syntax-node/expression/index.test.ts
@@ -0,0 +1,118 @@
+import {
+  createIdentifierNode,
+  createNumberNode,
+  createStringNode,
+  createPrefixNode,
+  createInfixNode,
+  createFunctionNode,
+  createCallNode,
+  createAssignmentNode,
+} from "./";
+import type {
+  IdentifierNode,
+  ExpressionNode,
+} from "./";
+import type {
+  BlockNode,
+} from "../group";
+import { fakePos } from "../testing/fixtures";
+
+const cases = [
+  {
+    name: "identifier",
+    node: createIdentifierNode({ value: "foo" }, fakePos, fakePos),
+    expected: {
+      type: "identifier",
+      fields: {
+        value: "foo",
+      },
+      range: { begin: fakePos, end: fakePos },
+    },
+  },
+  {
+    name: "number",
+    node: createNumberNode({ value: 42 }, fakePos, fakePos),
+    expected: {
+      type: "number",
+      fields: {
+        value: 42,
+      },
+      range: { begin: fakePos, end: fakePos },
+    },
+  },
+  {
+    name: "string",
+    node: createStringNode({ value: "foo" }, fakePos, fakePos),
+    expected: {
+      type: "string",
+      fields: {
+        value: "foo",
+      },
+      range: { begin: fakePos, end: fakePos },
+    },
+  },
+  {
+    name: "prefix",
+    node: createPrefixNode({ prefix: "+", right: {} as ExpressionNode }, fakePos, fakePos),
+    expected: {
+      type: "prefix",
+      fields: {
+        prefix: "+",
+        right: {},
+      },
+      range: { begin: fakePos, end: fakePos },
+    },
+  },
+  {
+    name: "infix",
+    node: createInfixNode({ infix: "+", left: {} as ExpressionNode, right: {} as ExpressionNode }, fakePos, fakePos),
+    expected: {
+      type: "infix",
+      fields: {
+        infix: "+",
+        left: {},
+        right: {},
+      },
+      range: { begin: fakePos, end: fakePos },
+    },
+  },
+  {
+    name: "function",
+    node: createFunctionNode({ parameters: [] as IdentifierNode[], body: {} as BlockNode }, fakePos, fakePos),
+    expected: {
+      type: "function",
+      fields: {
+        parameters: [],
+        body: {},
+      },
+      range: { begin: fakePos, end: fakePos },
+    },
+  },
+  {
+    name: "call",
+    node: createCallNode({ func: {} as IdentifierNode, args: [] as ExpressionNode[] }, fakePos, fakePos),
+    expected: {
+      type: "call",
+      fields: {
+        func: {},
+        args: [],
+      },
+      range: { begin: fakePos, end: fakePos },
+    },
+  },
+  {
+    name: "assignment",
+    node: createAssignmentNode({ left: {} as IdentifierNode, right: {} as ExpressionNode }, fakePos, fakePos),
+    expected: {
+      type: "assignment",
+      fields: {
+        left: {},
+        right: {},
+      },
+      range: { begin: fakePos, end: fakePos },
+    },
+  },
+];
+it.each(cases)("create $name node", ({ node, expected }) => {
+  expect(node).toEqual(expected);
+});
diff --git a/src/parser/syntax-node/expression/index.ts b/src/parser/syntax-node/expression/index.ts
new file mode 100644
index 0000000..6250ee7
--- /dev/null
+++ b/src/parser/syntax-node/expression/index.ts
@@ -0,0 +1,35 @@
+import type { SyntaxNodeBase, CreateNode } from "../base";
+import { createNodeCreator } from "../base";
+import type { BlockNode } from "../group";
+
+export type Prefix = "+" | "-" | "!";
+export type Infix = "+" | "-" | "*" | "/" | "=" | "==" | "!=" | ">" | "<" | ">=" | "<=";
+
+export type ExpressionNode = IdentifierNode
+  | NumberNode
+  | BooleanNode
+  | StringNode
+  | PrefixNode
+  | InfixNode
+  | FunctionNode
+  | CallNode
+  | AssignmentNode;
+
+export interface IdentifierNode extends SyntaxNodeBase<"identifier", { value: string }> {};
+export interface NumberNode extends SyntaxNodeBase<"number", { value: number }> {};
+export interface BooleanNode extends SyntaxNodeBase<"boolean", { value: boolean }> {};
+export interface StringNode extends SyntaxNodeBase<"string", { value: string }> {};
+export interface PrefixNode extends SyntaxNodeBase<"prefix", { prefix: Prefix, right: ExpressionNode }> {};
+export interface InfixNode extends SyntaxNodeBase<"infix", { infix: Infix, left: ExpressionNode, right: ExpressionNode }> {};
+export interface FunctionNode extends SyntaxNodeBase<"function", { parameters: IdentifierNode[], body: BlockNode }> {};
+export interface CallNode extends SyntaxNodeBase<"call", { func: IdentifierNode | FunctionNode, args: ExpressionNode[] }> {};
+export interface AssignmentNode extends SyntaxNodeBase<"assignment", { left: IdentifierNode, right: ExpressionNode }> {};
+
+export const createIdentifierNode: CreateNode<IdentifierNode> = createNodeCreator<IdentifierNode>("identifier");
+export const createNumberNode: CreateNode<NumberNode> = createNodeCreator<NumberNode>("number");
+export const createStringNode: CreateNode<StringNode> = createNodeCreator<StringNode>("string");
+export const createPrefixNode: CreateNode<PrefixNode> = createNodeCreator<PrefixNode>("prefix");
+export const createInfixNode: CreateNode<InfixNode> = createNodeCreator<InfixNode>("infix");
+export const createFunctionNode: CreateNode<FunctionNode> = createNodeCreator<FunctionNode>("function");
+export const createCallNode: CreateNode<CallNode> = createNodeCreator<CallNode>("call");
+export const createAssignmentNode: CreateNode<AssignmentNode> = createNodeCreator<AssignmentNode>("assignment");
diff --git a/src/parser/syntax-node/group/index.test.ts b/src/parser/syntax-node/group/index.test.ts
new file mode 100644
index 0000000..0187f3c
--- /dev/null
+++ b/src/parser/syntax-node/group/index.test.ts
@@ -0,0 +1,33 @@
+import {
+  createProgramNode,
+  createBlockNode,
+} from "./";
+import { fakePos } from "../testing/fixtures";
+
+const cases = [
+  {
+    name: "program",
+    node: createProgramNode({ statements: [] }, fakePos, fakePos),
+    expected: {
+      type: "program",
+      fields: {
+        statements: [],
+      },
+      range: { begin: fakePos, end: fakePos },
+    },
+  },
+  {
+    name: "block",
+    node: createBlockNode({ statements: [] }, fakePos, fakePos),
+    expected: {
+      type: "block",
+      fields: {
+        statements: [],
+      },
+      range: { begin: fakePos, end: fakePos },
+    },
+  },
+];
+it.each(cases)("create $name node", ({ node, expected }) => {
+  expect(node).toEqual(expected);
+});
diff --git a/src/parser/syntax-node/group/index.ts b/src/parser/syntax-node/group/index.ts
new file mode 100644
index 0000000..77a24ef
--- /dev/null
+++ b/src/parser/syntax-node/group/index.ts
@@ -0,0 +1,12 @@
+import type { SyntaxNodeBase, CreateNode } from "../base";
+import { createNodeCreator } from "../base";
+
+export type GroupNode = ProgramNode | BlockNode;
+
+/** a root node for a syntax tree of a program */
+export interface ProgramNode extends SyntaxNodeBase<"program", { statements: any[] }> {};
+/** a group of statements */
+export interface BlockNode extends SyntaxNodeBase<"block", { statements: any[] }> {};
+
+export const createProgramNode: CreateNode<ProgramNode> = createNodeCreator<ProgramNode>("program");
+export const createBlockNode: CreateNode<BlockNode> = createNodeCreator<BlockNode>("block");
diff --git a/src/parser/syntax-node/index.ts b/src/parser/syntax-node/index.ts
new file mode 100644
index 0000000..cdf0e22
--- /dev/null
+++ b/src/parser/syntax-node/index.ts
@@ -0,0 +1,12 @@
+import type { GroupNode } from "./group";
+import type { StatementNode } from "./statement";
+import type { ExpressionNode } from "./expression";
+
+export type SyntaxNode = GroupNode | StatementNode | ExpressionNode;
+
+export * from "./group";
+export type * from "./group";
+export * from "./statement";
+export type * from "./statement";
+export * from "./expression";
+export type * from "./expression";
diff --git a/src/parser/syntax-node/statement/index.test.ts b/src/parser/syntax-node/statement/index.test.ts
new file mode 100644
index 0000000..9e873d4
--- /dev/null
+++ b/src/parser/syntax-node/statement/index.test.ts
@@ -0,0 +1,65 @@
+import {
+  createBranchNode,
+  createReturnNode,
+  createExpressionStatementNode,
+} from "./";
+import type {
+  ExpressionNode,
+} from "../expression";
+import type {
+  BlockNode,
+} from "../group";
+import { fakePos } from "../testing/fixtures";
+
+const cases = [
+  {
+    name: "branch",
+    node: createBranchNode({ predicate: {} as ExpressionNode, consequence: {} as BlockNode }, fakePos, fakePos),
+    expected: {
+      type: "branch",
+      fields: {
+        predicate: {},
+        consequence: {},
+      },
+      range: { begin: fakePos, end: fakePos },
+    },
+  },
+  {
+    name: "branch with alternative",
+    node: createBranchNode({ predicate: {} as ExpressionNode, consequence: {} as BlockNode, alternative: {} as BlockNode }, fakePos, fakePos),
+    expected: {
+      type: "branch",
+      fields: {
+        predicate: {},
+        consequence: {},
+        alternative: {},
+      },
+      range: { begin: fakePos, end: fakePos },
+    },
+  },
+  {
+    name: "return",
+    node: createReturnNode({ expression: {} as ExpressionNode }, fakePos, fakePos),
+    expected: {
+      type: "return",
+      fields: {
+        expression: {},
+      },
+      range: { begin: fakePos, end: fakePos },
+    },
+  },
+  {
+    name: "expression statement",
+    node: createExpressionStatementNode({ expression: {} as ExpressionNode }, fakePos, fakePos),
+    expected: {
+      type: "expression statement",
+      fields: {
+        expression: {},
+      },
+      range: { begin: fakePos, end: fakePos },
+    },
+  },
+];
+it.each(cases)("create $name node", ({ node, expected }) => {
+  expect(node).toEqual(expected);
+});
diff --git a/src/parser/syntax-node/statement/index.ts b/src/parser/syntax-node/statement/index.ts
new file mode 100644
index 0000000..88b0fd5
--- /dev/null
+++ b/src/parser/syntax-node/statement/index.ts
@@ -0,0 +1,15 @@
+import type { SyntaxNodeBase, CreateNode } from "../base";
+import { createNodeCreator } from "../base";
+import type { BlockNode } from "../group";
+import type { ExpressionNode } from "../expression";
+
+export type StatementNode = BranchNode | ReturnNode | ExpressionStatementNode;
+
+export interface BranchNode extends SyntaxNodeBase<"branch", { predicate: ExpressionNode, consequence: BlockNode, alternative?: BlockNode }> {};
+export interface ReturnNode extends SyntaxNodeBase<"return", { expression: ExpressionNode }> {};
+/** A wrapper type to treat a single expression as a statement. */
+export interface ExpressionStatementNode extends SyntaxNodeBase<"expression statement", { expression: ExpressionNode }> {};
+
+export const createBranchNode: CreateNode<BranchNode> = createNodeCreator<BranchNode>("branch");
+export const createReturnNode: CreateNode<ReturnNode> = createNodeCreator<ReturnNode>("return");
+export const createExpressionStatementNode: CreateNode<ExpressionStatementNode> = createNodeCreator<ExpressionStatementNode>("expression statement");
diff --git a/src/parser/syntax-node/testing/fixtures/index.ts b/src/parser/syntax-node/testing/fixtures/index.ts
new file mode 100644
index 0000000..e6928c3
--- /dev/null
+++ b/src/parser/syntax-node/testing/fixtures/index.ts
@@ -0,0 +1 @@
+export const fakePos = { col: 0, row: 0 };
diff --git a/src/parser/token-reader/index.ts b/src/parser/token-reader/index.ts
index f1025a4..015b0c0 100644
--- a/src/parser/token-reader/index.ts
+++ b/src/parser/token-reader/index.ts
@@ -1,6 +1,7 @@
 import Lexer from "../../lexer";
 import type { TokenType } from "../../lexer";
 
+/** @deprecated */
 export default class TokenReader {
   private readonly lexer: Lexer;
   private token: TokenType;
@@ -10,14 +11,17 @@ export default class TokenReader {
     this.token = lexer.getToken();
   }
 
+  /** @deprecated */
   isEnd(): boolean {
     return this.token.type === "end";
   }
 
+  /** @deprecated */
   read(): TokenType {
     return this.token;
   }
 
+  /** @deprecated */
   next(): void {
     this.token = this.lexer.getToken();
   }