This README.md contains high-level detail
about the coursework and language
from the submitted report.
See individual .mds for detail on the:
Install dependencies:
npm i- A form of g++ in ENV (e.g. MinGW)
For hello world:
npm start .\test\scripts\hello-world.ts
Or, in general:
npm start <script>
The scope of this coursework is to implement a compiler for a source language that has no run-time errors but may issue run-time warnings.
The source language for the compiler is chosen to be a subset of TypeScript. TypeScript is an open-source programming language, which is a strict syntactical superset of JavaScript and adds static typing to the language [1], as opposed to JavaScript’s no static type nature [2]. Due to the open-source nature of it, access to its language specification is public. Along with this, since the language is widely used, running [3] and comparing original code during tests [4] will be made easier. The subset chosen is described in the Description of Source Language section.
The target language chosen is C. This was mainly chosen due to the low-level nature of the language, allowing for complex algorithms to be executed at close to machine clock. Also, development is made easier due to existing familiarity with the language from previously assessed coursework, most notably CS1PR16 C/C++ labs and CS1FC16 sorting coursework in C.
The language chosen for the compiler is also TypeScript. This was done to build more familiarity with the programming language, with a view of using it for future projects (most notably, the upcoming final year project). Also, with the rather simple nature of the chosen subset of the language, and the performance of the development machines, some efficiency is traded for greater flexibility of the compiler.
For the compiler to be implemented and tested, the source language is defined. Since TypeScript has a very large grammar, a subset of it is chosen and defined.
The main feature required in the subset is output. TypeScript allows standard output
to the command-line using its console.log(content) function. As a result, both console
and log are added as reserved keywords for the compiler to detect output to stdout. In this
case, content can be either a constant or a variable, as seen in Figure 1 and Figure 2
respectively.
console.log("Hello, world!")Figure 1. Standard Output with Constant Example
let num: number = 3
console.log(num)Figure 2. Standard Output with Identifier Example
Along with this, the let keyword is added to the reserved list, for use in variable declarations. TypeScript allows multiple types of variables to be declared, and the main ones chosen in the subset are string and number types. Although in Typescript the number types are stored as floating-point values [5], they will be restricted to integers for this application. Along with this, a constant may be added to the declaration to assign a value to the newly declared variable.
Examples of valid declaration statements are shown in Figure 3.
let num: number
let str: stringFigure 3. Declare Statements
Examples of valid declare and assign statements are shown in Figure 4.
let num: number = 3
let str: string = "Hello, world!"Figure 4. Declare and Assign Statements
Assignment may be performed outside of the declaration, as seen in Figure 5.
let str: string
str = "Hello, world!"Figure 5. Assign Statements with Constants
Previous assignment statements use constants as the value. Valid assignment statements also allow identifiers to be used, as seen in Figure 6.
let str: string
let hello: string = "Hello, world!"
str = helloFigure 6. Assign Statements with Identifiers
Arithmetic may be performed in assignment statements as well on number typed variables, as seen in Figure 7.
let a: number = 1
let b: number = 2
let c: number
c = a + bFigure 7. Assign Statements with Arithmetic
Along with addition, other available arithmetic operations in the subset are: subtraction, multiplication, incrementation, decrementation.