102 lines
2.8 KiB
TypeScript
102 lines
2.8 KiB
TypeScript
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import { SQLFragment, TruthySQLFragment } from '../generic/sql-fragment';
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function doesNotWantLeadingSpace(str: string): boolean {
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return /^[;,)]/.test(str);
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}
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function doesNotWantTrailingSpace(str: string): boolean {
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return /\($/.test(str);
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}
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/**
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* Joins an array of strings with a single space between them,
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* except for:
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*
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* - Strings starting with ';', ',' and ')', which do not get a leading space.
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* - Strings ending with '(', which do not get a trailing space.
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*
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* @param {string[]} parts
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* @returns {string}
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* @private
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*/
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function singleSpaceJoinHelper(parts: string[]): string {
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return parts.reduce(
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({ skipNextLeadingSpace, result }, part) => {
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if (skipNextLeadingSpace || doesNotWantLeadingSpace(part)) {
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result += part.trim();
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} else {
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result += ` ${part.trim()}`;
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}
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return {
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skipNextLeadingSpace: doesNotWantTrailingSpace(part),
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result
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};
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},
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{
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skipNextLeadingSpace: true,
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result: ''
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}
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).result;
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}
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/**
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* Joins an array with a single space, auto trimming when needed.
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*
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* Certain elements do not get leading/trailing spaces.
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*
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* @param {SQLFragment[]} array The array to be joined. Falsy values are skipped. If an
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* element is another array, this function will be called recursively on that array.
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* Otherwise, if a non-string, non-falsy value is present, a TypeError will be thrown.
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*
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* @returns {string} The joined string.
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*
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* @private
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*/
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export function joinSQLFragments(array: SQLFragment[]): string {
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if (array.length === 0) return '';
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const truthyArray: TruthySQLFragment[] = array.filter(
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(x): x is string | SQLFragment[] => !!x
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);
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const flattenedArray: string[] = truthyArray.map(
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(fragment: TruthySQLFragment) => {
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if (Array.isArray(fragment)) {
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return joinSQLFragments(fragment);
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}
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return fragment;
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}
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);
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// Ensure strings
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for (const fragment of flattenedArray) {
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if (fragment && typeof fragment !== 'string') {
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throw new JoinSQLFragmentsError(
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flattenedArray,
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fragment,
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`Tried to construct a SQL string with a non-string, non-falsy fragment (${fragment}).`
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);
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}
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}
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// Trim fragments
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const trimmedArray = flattenedArray.map(x => x.trim());
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// Skip full-whitespace fragments (empty after the above trim)
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const nonEmptyStringArray = trimmedArray.filter(x => x !== '');
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return singleSpaceJoinHelper(nonEmptyStringArray);
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}
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export class JoinSQLFragmentsError extends TypeError {
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args: SQLFragment[];
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fragment: any; // iirc this error is only used when we get an invalid fragment.
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constructor(args: SQLFragment[], fragment: any, message: string) {
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super(message);
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this.args = args;
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this.fragment = fragment;
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this.name = 'JoinSQLFragmentsError';
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}
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}
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