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refactor script compilation to make it easy to add new expressions #41 #53

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This commit is contained in:
undergroundwires
2021-03-05 15:52:49 +01:00
parent 1f8a0cf9ab
commit 646db90585
42 changed files with 1312 additions and 582 deletions
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35
src/application/Parser/Script/Compiler/Expressions/Expression/Expression.ts Normal file
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import { ExpressionPosition } from './ExpressionPosition';
import { ExpressionArguments, IExpression } from './IExpression';
export type ExpressionEvaluator = (args?: ExpressionArguments) => string;
export class Expression implements IExpression {
constructor(
public readonly position: ExpressionPosition,
public readonly evaluator: ExpressionEvaluator,
public readonly parameters: readonly string[] = new Array<string>()) {
if (!position) {
throw new Error('undefined position');
}
if (!evaluator) {
throw new Error('undefined evaluator');
}
}
public evaluate(args?: ExpressionArguments): string {
args = filterUnusedArguments(this.parameters, args);
return this.evaluator(args);
}
}
function filterUnusedArguments(
parameters: readonly string[], args: ExpressionArguments): ExpressionArguments {
let result: ExpressionArguments = {};
for (const parameter of Object.keys(args)) {
if (parameters.includes(parameter)) {
result = {
...result,
[parameter]: args[parameter],
};
}
}
return result;
}

15
src/application/Parser/Script/Compiler/Expressions/Expression/ExpressionPosition.ts Normal file
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export class ExpressionPosition {
constructor(
public readonly start: number,
public readonly end: number) {
if (start === end) {
throw new Error(`no length (start = end = ${start})`);
}
if (start > end) {
throw Error(`start (${start}) after end (${end})`);
}
if (start < 0) {
throw Error(`negative start position: ${start}`);
}
}
}

12
src/application/Parser/Script/Compiler/Expressions/Expression/IExpression.ts Normal file
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import { ExpressionPosition } from './ExpressionPosition';
export interface IExpression {
readonly position: ExpressionPosition;
readonly parameters?: readonly string[];
evaluate(args?: ExpressionArguments): string;
}
export interface ExpressionArguments {
readonly [parameter: string]: string;
}

54
src/application/Parser/Script/Compiler/Expressions/ExpressionsCompiler.ts
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@@ -1,31 +1,49 @@
import { IExpressionsCompiler, ParameterValueDictionary } from './IExpressionsCompiler';
import { generateIlCode, IILCode } from './ILCode';
import { IExpression } from './Expression/IExpression';
import { IExpressionParser } from './Parser/IExpressionParser';
import { CompositeExpressionParser } from './Parser/CompositeExpressionParser';
export class ExpressionsCompiler implements IExpressionsCompiler {
public static readonly instance: IExpressionsCompiler = new ExpressionsCompiler();
protected constructor() { }
public constructor(private readonly extractor: IExpressionParser = new CompositeExpressionParser()) { }
public compileExpressions(code: string, parameters?: ParameterValueDictionary): string {
let intermediateCode = generateIlCode(code);
intermediateCode = substituteParameters(intermediateCode, parameters);
return intermediateCode.compile();
const expressions = this.extractor.findExpressions(code);
const requiredParameterNames = expressions.map((e) => e.parameters).filter((p) => p).flat();
const uniqueParameterNames = Array.from(new Set(requiredParameterNames));
ensureRequiredArgsProvided(uniqueParameterNames, parameters);
return compileExpressions(expressions, code, parameters);
}
}
function substituteParameters(intermediateCode: IILCode, parameters: ParameterValueDictionary): IILCode {
const parameterNames = intermediateCode.getUniqueParameterNames();
ensureValuesProvided(parameterNames, parameters);
for (const parameterName of parameterNames) {
const parameterValue = parameters[parameterName];
intermediateCode = intermediateCode.substituteParameter(parameterName, parameterValue);
function compileExpressions(expressions: IExpression[], code: string, parameters?: ParameterValueDictionary) {
let compiledCode = '';
expressions = expressions
.slice() // copy the array to not mutate the parameter
.sort((a, b) => b.position.start - a.position.start);
let index = 0;
while (index !== code.length) {
const nextExpression = expressions.pop();
if (nextExpression) {
compiledCode += code.substring(index, nextExpression.position.start);
const expressionCode = nextExpression.evaluate(parameters);
compiledCode += expressionCode;
index = nextExpression.position.end;
} else {
compiledCode += code.substring(index, code.length);
break;
}
}
return intermediateCode;
return compiledCode;
}
function ensureValuesProvided(names: string[], nameValues: ParameterValueDictionary) {
nameValues = nameValues || {};
const notProvidedNames = names.filter((name) => !Boolean(nameValues[name]));
if (notProvidedNames.length) {
throw new Error(`parameter value(s) not provided for: ${printList(notProvidedNames)}`);
function ensureRequiredArgsProvided(parameters: readonly string[], args: ParameterValueDictionary) {
parameters = parameters || [];
args = args || {};
if (!parameters.length) {
return;
}
const notProvidedParameters = parameters.filter((parameter) => !Boolean(args[parameter]));
if (notProvidedParameters.length) {
throw new Error(`parameter value(s) not provided for: ${printList(notProvidedParameters)}`);
}
}

73
src/application/Parser/Script/Compiler/Expressions/ILCode.ts
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@@ -1,73 +0,0 @@
export interface IILCode {
compile(): string;
getUniqueParameterNames(): string[];
substituteParameter(parameterName: string, parameterValue: string): IILCode;
}
export function generateIlCode(rawText: string): IILCode {
const ilCode = generateIl(rawText);
return new ILCode(ilCode);
}
class ILCode implements IILCode {
private readonly ilCode: string;
constructor(ilCode: string) {
this.ilCode = ilCode;
}
public substituteParameter(parameterName: string, parameterValue: string): IILCode {
const newCode = substituteParameter(this.ilCode, parameterName, parameterValue);
return new ILCode(newCode);
}
public getUniqueParameterNames(): string[] {
return getUniqueParameterNames(this.ilCode);
}
public compile(): string {
ensureNoExpressionLeft(this.ilCode);
return this.ilCode;
}
}
// Trim each expression and put them inside "{{exp|}}" e.g. "{{ $hello }}" becomes "{{exp|$hello}}"
function generateIl(rawText: string): string {
return rawText.replace(/\{\{([\s]*[^;\s\{]+[\s]*)\}\}/g, (_, match) => {
return `\{\{exp|${match.trim()}\}\}`;
});
}
// finds all "{{exp|..}} left"
function ensureNoExpressionLeft(ilCode: string) {
const allSubstitutions = ilCode.matchAll(/\{\{exp\|(.*?)\}\}/g);
const allMatches = Array.from(allSubstitutions, (match) => match[1]);
const uniqueExpressions = getDistinctValues(allMatches);
if (uniqueExpressions.length > 0) {
throw new Error(`unknown expression: ${printList(uniqueExpressions)}`);
}
}
// Parses all distinct usages of {{exp|$parameterName}}
function getUniqueParameterNames(ilCode: string) {
const allSubstitutions = ilCode.matchAll(/\{\{exp\|\$([^;\s\{]+[\s]*)\}\}/g);
const allParameters = Array.from(allSubstitutions, (match) => match[1]);
const uniqueParameterNames = getDistinctValues(allParameters);
return uniqueParameterNames;
}
// substitutes {{exp|$parameterName}} to value of the parameter
function substituteParameter(ilCode: string, parameterName: string, parameterValue: string) {
const pattern = `{{exp|$${parameterName}}}`;
return ilCode.split(pattern).join(parameterValue); // as .replaceAll() is not yet supported by TS
}
function getDistinctValues(values: readonly string[]): string[] {
return values.filter((value, index, self) => {
return self.indexOf(value) === index;
});
}
function printList(list: readonly string[]): string {
return `"${list.join('","')}"`;
}

23
src/application/Parser/Script/Compiler/Expressions/Parser/CompositeExpressionParser.ts Normal file
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import { IExpression } from '../Expression/IExpression';
import { IExpressionParser } from './IExpressionParser';
import { ParameterSubstitutionParser } from '../SyntaxParsers/ParameterSubstitutionParser';
const parsers = [
new ParameterSubstitutionParser(),
];
export class CompositeExpressionParser implements IExpressionParser {
public constructor(private readonly leafs: readonly IExpressionParser[] = parsers) {
if (leafs.some((leaf) => !leaf)) { throw new Error('undefined leaf'); }
}
public findExpressions(code: string): IExpression[] {
const expressions = new Array<IExpression>();
for (const parser of this.leafs) {
const newExpressions = parser.findExpressions(code);
if (newExpressions && newExpressions.length) {
expressions.push(...newExpressions);
}
}
return expressions;
}
}

5
src/application/Parser/Script/Compiler/Expressions/Parser/IExpressionParser.ts Normal file
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import { IExpression } from '../Expression/IExpression';
export interface IExpressionParser {
findExpressions(code: string): IExpression[];
}

35
src/application/Parser/Script/Compiler/Expressions/Parser/RegexParser.ts Normal file
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import { IExpressionParser } from './IExpressionParser';
import { ExpressionPosition } from '../Expression/ExpressionPosition';
import { IExpression } from '../Expression/IExpression';
import { Expression, ExpressionEvaluator } from '../Expression/Expression';
export abstract class RegexParser implements IExpressionParser {
protected abstract readonly regex: RegExp;
public findExpressions(code: string): IExpression[] {
return Array.from(this.findRegexExpressions(code));
}
protected abstract buildExpression(match: RegExpMatchArray): IPrimitiveExpression;
private* findRegexExpressions(code: string): Iterable<IExpression> {
const matches = Array.from(code.matchAll(this.regex));
for (const match of matches) {
const startPos = match.index;
const endPos = startPos + match[0].length;
let position: ExpressionPosition;
try {
position = new ExpressionPosition(startPos, endPos);
} catch (error) {
throw new Error(`[${this.constructor.name}] invalid script position: ${error.message}\nRegex ${this.regex}\nCode: ${code}`);
}
const primitiveExpression = this.buildExpression(match);
const expression = new Expression(position, primitiveExpression.evaluator, primitiveExpression.parameters);
yield expression;
}
}
}
export interface IPrimitiveExpression {
evaluator: ExpressionEvaluator;
parameters?: readonly string[];
}

12
src/application/Parser/Script/Compiler/Expressions/SyntaxParsers/ParameterSubstitutionParser.ts Normal file
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import { RegexParser, IPrimitiveExpression } from '../Parser/RegexParser';
export class ParameterSubstitutionParser extends RegexParser {
protected readonly regex = /{{\s*\$\s*([^}| ]+)\s*}}/g;
protected buildExpression(match: RegExpMatchArray): IPrimitiveExpression {
const parameterName = match[1];
return {
parameters: [ parameterName ],
evaluator: (args) => args[parameterName],
};
}
}