Created
October 11, 2020 15:26
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Python like parser written in Typescript
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| const code: string = ` | |
| if test = "brut": | |
| print "yay" | |
| if message = "Hello": | |
| print "World" | |
| else: | |
| print "brush" | |
| set "test" | |
| else: | |
| print "hobo" | |
| print "Hello world" | |
| `; | |
| const formated: string[] = code | |
| .split(/\r?\n/g) | |
| .filter((x: string) => x.trim().length > 0); | |
| type type = 'Program' | 'Node' | 'Block'; | |
| type state = -1 | 0 | 1 | 2; | |
| interface AST { | |
| type: type, | |
| raw: string, | |
| line: number, | |
| tabs: number, | |
| children: AST[], | |
| parent?: AST, | |
| } | |
| const ast: AST = { | |
| type: 'Program', | |
| raw: '', | |
| line: -1, | |
| tabs: -1, | |
| children: [], | |
| }; | |
| let tabSize: number; | |
| let oldTabSize: number = -1; | |
| function getSizeTabs(line: string): number { | |
| if (!tabSize) return 0; | |
| const matched: string[] = line.match(/^\s+/) || ['']; | |
| return matched[0].length / tabSize; | |
| } | |
| function getParent(ast: AST, iterations: number): AST { | |
| if (iterations === 0) return ast; | |
| else { | |
| if (!ast.parent) return ast; | |
| return getParent(ast.parent, iterations - 1); | |
| } | |
| } | |
| function parse(code: string[], index: number, ast: AST): typeof parse | null { | |
| const line: string = code[index]; | |
| if (!line) return null; | |
| if (!tabSize || tabSize === 0) { | |
| const matched: string[] = line.match(/^\s+/) || ['']; | |
| tabSize = matched[0].length; | |
| } | |
| const tabs: number = getSizeTabs(line); | |
| let state: state = -1; | |
| if (oldTabSize > tabs) state = 0 | |
| else if (oldTabSize === tabs) state = 2; | |
| else if (oldTabSize < tabs) state = 1; | |
| const parentsNumber: number = Math.abs(tabs - oldTabSize); | |
| oldTabSize = tabs; | |
| const trimLine: string = line.trim(); | |
| if (state === 0) ast = getParent(ast, parentsNumber); | |
| if (trimLine.endsWith(':')) { | |
| ast.children.push({ | |
| type: 'Node', | |
| raw: trimLine, | |
| line: index, | |
| tabs: tabs, | |
| children: [], | |
| parent: ast, | |
| }); | |
| return parse(code, index + 1, ast.children.slice(-1)[0]); | |
| } | |
| ast.children.push({ | |
| type: 'Block', | |
| raw: trimLine, | |
| line: index, | |
| tabs: tabs, | |
| children: [], | |
| parent: ast, | |
| }); | |
| return parse(code, index + 1, ast); | |
| } | |
| parse(formated, 0, ast); | |
| function printAST(ast: AST) { | |
| if (!ast) return; | |
| for (const child of ast.children) { | |
| const tabs: string = new Array(child.tabs).fill(' '.repeat(tabSize)).join(''); | |
| if (child.raw.endsWith(':')) console.log(tabs + child.raw.slice(0, child.raw.length - 1) + ' {'); | |
| else console.log(tabs + child.raw); | |
| printAST(child); | |
| if (child.raw.endsWith(':')) console.log(tabs + '}'); | |
| } | |
| } | |
| printAST(ast); |
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