export function longestCommonPrefix(str1, str2) {

let i;

for (i = 0; i < str1.length && i < str2.length; i++) {

if (str1[i] != str2[i]) {

return str1.slice(0, i);

}

}

return str1.slice(0, i);

}

export function longestCommonSuffix(str1, str2) {

let i;

// Unlike longestCommonPrefix, we need a special case to handle all scenarios

// where we return the empty string since str1.slice(-0) will return the

// entire string.

if (!str1 || !str2 || str1[str1.length - 1] != str2[str2.length - 1]) {

return '';

}

for (i = 0; i < str1.length && i < str2.length; i++) {

if (str1[str1.length - (i + 1)] != str2[str2.length - (i + 1)]) {

return str1.slice(-i);

}

}

return str1.slice(-i);

}

export function replacePrefix(string, oldPrefix, newPrefix) {

if (string.slice(0, oldPrefix.length) != oldPrefix) {

throw Error(`string ${JSON.stringify(string)} doesn't start with prefix ${JSON.stringify(oldPrefix)}; this is a bug`);

}

return newPrefix + string.slice(oldPrefix.length);

}

export function replaceSuffix(string, oldSuffix, newSuffix) {

if (!oldSuffix) {

return string + newSuffix;

}

if (string.slice(-oldSuffix.length) != oldSuffix) {

throw Error(`string ${JSON.stringify(string)} doesn't end with suffix ${JSON.stringify(oldSuffix)}; this is a bug`);

}

return string.slice(0, -oldSuffix.length) + newSuffix;

}

export function removePrefix(string, oldPrefix) {

return replacePrefix(string, oldPrefix, '');

}

export function removeSuffix(string, oldSuffix) {

return replaceSuffix(string, oldSuffix, '');

}

export function maximumOverlap(string1, string2) {

return string2.slice(0, overlapCount(string1, string2));

}

// Nicked from https://stackoverflow.com/a/60422853/1709587

function overlapCount(a, b) {

// Deal with cases where the strings differ in length

let startA = 0;

if (a.length > b.length) { startA = a.length - b.length; }

let endB = b.length;

if (a.length < b.length) { endB = a.length; }

// Create a back-reference for each index

// that should be followed in case of a mismatch.

// We only need B to make these references:

let map = Array(endB);

let k = 0; // Index that lags behind j

map[0] = 0;

for (let j = 1; j < endB; j++) {

if (b[j] == b[k]) {

map[j] = map[k]; // skip over the same character (optional optimisation)

} else {

map[j] = k;

}

while (k > 0 && b[j] != b[k]) { k = map[k]; }

if (b[j] == b[k]) { k++; }

}

// Phase 2: use these references while iterating over A

k = 0;

for (let i = startA; i < a.length; i++) {

while (k > 0 && a[i] != b[k]) { k = map[k]; }

if (a[i] == b[k]) { k++; }

}

return k;

}

/**

* Returns true if the string consistently uses Windows line endings.

*/

export function hasOnlyWinLineEndings(string) {

return string.includes('\r\n') && !string.startsWith('\n') && !string.match(/[^\r]\n/);

}

/**

* Returns true if the string consistently uses Unix line endings.

*/

export function hasOnlyUnixLineEndings(string) {

return !string.includes('\r\n') && string.includes('\n');

}