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fast-diff - npm Package Compare versions

Comparing version 1.2.0 to 1.3.0

LICENSE

23

diff.d.ts
declare function diff(
text1: string,
text2: string,
cursorPos?: number | diff.CursorInfo
text1: string,
text2: string,
cursorPos?: number | diff.CursorInfo,
cleanup?: boolean
): diff.Diff[];
declare namespace diff {
type Diff = [-1 | 0 | 1, string];
type Diff = [-1 | 0 | 1, string];
const DELETE: -1;
const INSERT: 1;
const EQUAL: 0;
const DELETE: -1;
const INSERT: 1;
const EQUAL: 0;
interface CursorInfo {
oldRange: { index: number; length: number };
newRange: { index: number; length: number };
}
interface CursorInfo {
oldRange: { index: number; length: number };
newRange: { index: number; length: number };
}
}
export = diff;

@@ -26,3 +26,2 @@ /**

/**

@@ -37,3 +36,2 @@ * The data structure representing a diff is an array of tuples:

/**

@@ -45,5 +43,6 @@ * Find the differences between two texts. Simplifies the problem by stripping

* @param {Int|Object} [cursor_pos] Edit position in text1 or object with more info
* @param {boolean} [cleanup] Apply semantic cleanup before returning.
* @return {Array} Array of diff tuples.
*/
function diff_main(text1, text2, cursor_pos, _fix_unicode) {
function diff_main(text1, text2, cursor_pos, cleanup, _fix_unicode) {
// Check for equality

@@ -87,6 +86,8 @@ if (text1 === text2) {

diff_cleanupMerge(diffs, _fix_unicode);
if (cleanup) {
diff_cleanupSemantic(diffs);
}
return diffs;
};
}
/**

@@ -120,3 +121,3 @@ * Find the differences between two texts. Assumes that the texts do not

[DIFF_EQUAL, shorttext],
[DIFF_INSERT, longtext.substring(i + shorttext.length)]
[DIFF_INSERT, longtext.substring(i + shorttext.length)],
];

@@ -133,3 +134,6 @@ // Swap insertions for deletions if diff is reversed.

// After the previous speedup, the character can't be an equality.
return [[DIFF_DELETE, text1], [DIFF_INSERT, text2]];
return [
[DIFF_DELETE, text1],
[DIFF_INSERT, text2],
];
}

@@ -154,5 +158,4 @@

return diff_bisect_(text1, text2);
};
}
/**

@@ -187,3 +190,3 @@ * Find the 'middle snake' of a diff, split the problem in two

// with the reverse path.
var front = (delta % 2 !== 0);
var front = delta % 2 !== 0;
// Offsets for start and end of k loop.

@@ -207,3 +210,4 @@ // Prevents mapping of space beyond the grid.

while (
x1 < text1_length && y1 < text2_length &&
x1 < text1_length &&
y1 < text2_length &&
text1.charAt(x1) === text2.charAt(y1)

@@ -245,4 +249,6 @@ ) {

while (
x2 < text1_length && y2 < text2_length &&
text1.charAt(text1_length - x2 - 1) === text2.charAt(text2_length - y2 - 1)
x2 < text1_length &&
y2 < text2_length &&
text1.charAt(text1_length - x2 - 1) ===
text2.charAt(text2_length - y2 - 1)
) {

@@ -276,6 +282,8 @@ x2++;

// number of diffs equals number of characters, no commonality at all.
return [[DIFF_DELETE, text1], [DIFF_INSERT, text2]];
};
return [
[DIFF_DELETE, text1],
[DIFF_INSERT, text2],
];
}
/**

@@ -301,5 +309,4 @@ * Given the location of the 'middle snake', split the diff in two parts

return diffs.concat(diffsb);
};
}
/**

@@ -341,5 +348,54 @@ * Determine the common prefix of two strings.

return pointermid;
};
}
/**
* Determine if the suffix of one string is the prefix of another.
* @param {string} text1 First string.
* @param {string} text2 Second string.
* @return {number} The number of characters common to the end of the first
* string and the start of the second string.
* @private
*/
function diff_commonOverlap_(text1, text2) {
// Cache the text lengths to prevent multiple calls.
var text1_length = text1.length;
var text2_length = text2.length;
// Eliminate the null case.
if (text1_length == 0 || text2_length == 0) {
return 0;
}
// Truncate the longer string.
if (text1_length > text2_length) {
text1 = text1.substring(text1_length - text2_length);
} else if (text1_length < text2_length) {
text2 = text2.substring(0, text1_length);
}
var text_length = Math.min(text1_length, text2_length);
// Quick check for the worst case.
if (text1 == text2) {
return text_length;
}
// Start by looking for a single character match
// and increase length until no match is found.
// Performance analysis: http://neil.fraser.name/news/2010/11/04/
var best = 0;
var length = 1;
while (true) {
var pattern = text1.substring(text_length - length);
var found = text2.indexOf(pattern);
if (found == -1) {
return best;
}
length += found;
if (
found == 0 ||
text1.substring(text_length - length) == text2.substring(0, length)
) {
best = length;
length++;
}
}
}
/**

@@ -380,5 +436,4 @@ * Determine the common suffix of two strings.

return pointermid;
};
}
/**

@@ -398,3 +453,3 @@ * Do the two texts share a substring which is at least half the length of the

if (longtext.length < 4 || shorttext.length * 2 < longtext.length) {
return null; // Pointless.
return null; // Pointless.
}

@@ -418,12 +473,17 @@

var j = -1;
var best_common = '';
var best_common = "";
var best_longtext_a, best_longtext_b, best_shorttext_a, best_shorttext_b;
while ((j = shorttext.indexOf(seed, j + 1)) !== -1) {
var prefixLength = diff_commonPrefix(
longtext.substring(i), shorttext.substring(j));
longtext.substring(i),
shorttext.substring(j)
);
var suffixLength = diff_commonSuffix(
longtext.substring(0, i), shorttext.substring(0, j));
longtext.substring(0, i),
shorttext.substring(0, j)
);
if (best_common.length < suffixLength + prefixLength) {
best_common = shorttext.substring(
j - suffixLength, j) + shorttext.substring(j, j + prefixLength);
best_common =
shorttext.substring(j - suffixLength, j) +
shorttext.substring(j, j + prefixLength);
best_longtext_a = longtext.substring(0, i - suffixLength);

@@ -437,4 +497,7 @@ best_longtext_b = longtext.substring(i + prefixLength);

return [
best_longtext_a, best_longtext_b,
best_shorttext_a, best_shorttext_b, best_common
best_longtext_a,
best_longtext_b,
best_shorttext_a,
best_shorttext_b,
best_common,
];

@@ -447,5 +510,13 @@ } else {

// First check if the second quarter is the seed for a half-match.
var hm1 = diff_halfMatchI_(longtext, shorttext, Math.ceil(longtext.length / 4));
var hm1 = diff_halfMatchI_(
longtext,
shorttext,
Math.ceil(longtext.length / 4)
);
// Check again based on the third quarter.
var hm2 = diff_halfMatchI_(longtext, shorttext, Math.ceil(longtext.length / 2));
var hm2 = diff_halfMatchI_(
longtext,
shorttext,
Math.ceil(longtext.length / 2)
);
var hm;

@@ -478,6 +549,265 @@ if (!hm1 && !hm2) {

return [text1_a, text1_b, text2_a, text2_b, mid_common];
};
}
/**
* Reduce the number of edits by eliminating semantically trivial equalities.
* @param {!Array.<!diff_match_patch.Diff>} diffs Array of diff tuples.
*/
function diff_cleanupSemantic(diffs) {
var changes = false;
var equalities = []; // Stack of indices where equalities are found.
var equalitiesLength = 0; // Keeping our own length var is faster in JS.
/** @type {?string} */
var lastequality = null;
// Always equal to diffs[equalities[equalitiesLength - 1]][1]
var pointer = 0; // Index of current position.
// Number of characters that changed prior to the equality.
var length_insertions1 = 0;
var length_deletions1 = 0;
// Number of characters that changed after the equality.
var length_insertions2 = 0;
var length_deletions2 = 0;
while (pointer < diffs.length) {
if (diffs[pointer][0] == DIFF_EQUAL) {
// Equality found.
equalities[equalitiesLength++] = pointer;
length_insertions1 = length_insertions2;
length_deletions1 = length_deletions2;
length_insertions2 = 0;
length_deletions2 = 0;
lastequality = diffs[pointer][1];
} else {
// An insertion or deletion.
if (diffs[pointer][0] == DIFF_INSERT) {
length_insertions2 += diffs[pointer][1].length;
} else {
length_deletions2 += diffs[pointer][1].length;
}
// Eliminate an equality that is smaller or equal to the edits on both
// sides of it.
if (
lastequality &&
lastequality.length <=
Math.max(length_insertions1, length_deletions1) &&
lastequality.length <= Math.max(length_insertions2, length_deletions2)
) {
// Duplicate record.
diffs.splice(equalities[equalitiesLength - 1], 0, [
DIFF_DELETE,
lastequality,
]);
// Change second copy to insert.
diffs[equalities[equalitiesLength - 1] + 1][0] = DIFF_INSERT;
// Throw away the equality we just deleted.
equalitiesLength--;
// Throw away the previous equality (it needs to be reevaluated).
equalitiesLength--;
pointer = equalitiesLength > 0 ? equalities[equalitiesLength - 1] : -1;
length_insertions1 = 0; // Reset the counters.
length_deletions1 = 0;
length_insertions2 = 0;
length_deletions2 = 0;
lastequality = null;
changes = true;
}
}
pointer++;
}
// Normalize the diff.
if (changes) {
diff_cleanupMerge(diffs);
}
diff_cleanupSemanticLossless(diffs);
// Find any overlaps between deletions and insertions.
// e.g: <del>abcxxx</del><ins>xxxdef</ins>
// -> <del>abc</del>xxx<ins>def</ins>
// e.g: <del>xxxabc</del><ins>defxxx</ins>
// -> <ins>def</ins>xxx<del>abc</del>
// Only extract an overlap if it is as big as the edit ahead or behind it.
pointer = 1;
while (pointer < diffs.length) {
if (
diffs[pointer - 1][0] == DIFF_DELETE &&
diffs[pointer][0] == DIFF_INSERT
) {
var deletion = diffs[pointer - 1][1];
var insertion = diffs[pointer][1];
var overlap_length1 = diff_commonOverlap_(deletion, insertion);
var overlap_length2 = diff_commonOverlap_(insertion, deletion);
if (overlap_length1 >= overlap_length2) {
if (
overlap_length1 >= deletion.length / 2 ||
overlap_length1 >= insertion.length / 2
) {
// Overlap found. Insert an equality and trim the surrounding edits.
diffs.splice(pointer, 0, [
DIFF_EQUAL,
insertion.substring(0, overlap_length1),
]);
diffs[pointer - 1][1] = deletion.substring(
0,
deletion.length - overlap_length1
);
diffs[pointer + 1][1] = insertion.substring(overlap_length1);
pointer++;
}
} else {
if (
overlap_length2 >= deletion.length / 2 ||
overlap_length2 >= insertion.length / 2
) {
// Reverse overlap found.
// Insert an equality and swap and trim the surrounding edits.
diffs.splice(pointer, 0, [
DIFF_EQUAL,
deletion.substring(0, overlap_length2),
]);
diffs[pointer - 1][0] = DIFF_INSERT;
diffs[pointer - 1][1] = insertion.substring(
0,
insertion.length - overlap_length2
);
diffs[pointer + 1][0] = DIFF_DELETE;
diffs[pointer + 1][1] = deletion.substring(overlap_length2);
pointer++;
}
}
pointer++;
}
pointer++;
}
}
var nonAlphaNumericRegex_ = /[^a-zA-Z0-9]/;
var whitespaceRegex_ = /\s/;
var linebreakRegex_ = /[\r\n]/;
var blanklineEndRegex_ = /\n\r?\n$/;
var blanklineStartRegex_ = /^\r?\n\r?\n/;
/**
* Look for single edits surrounded on both sides by equalities
* which can be shifted sideways to align the edit to a word boundary.
* e.g: The c<ins>at c</ins>ame. -> The <ins>cat </ins>came.
* @param {!Array.<!diff_match_patch.Diff>} diffs Array of diff tuples.
*/
function diff_cleanupSemanticLossless(diffs) {
/**
* Given two strings, compute a score representing whether the internal
* boundary falls on logical boundaries.
* Scores range from 6 (best) to 0 (worst).
* Closure, but does not reference any external variables.
* @param {string} one First string.
* @param {string} two Second string.
* @return {number} The score.
* @private
*/
function diff_cleanupSemanticScore_(one, two) {
if (!one || !two) {
// Edges are the best.
return 6;
}
// Each port of this function behaves slightly differently due to
// subtle differences in each language's definition of things like
// 'whitespace'. Since this function's purpose is largely cosmetic,
// the choice has been made to use each language's native features
// rather than force total conformity.
var char1 = one.charAt(one.length - 1);
var char2 = two.charAt(0);
var nonAlphaNumeric1 = char1.match(nonAlphaNumericRegex_);
var nonAlphaNumeric2 = char2.match(nonAlphaNumericRegex_);
var whitespace1 = nonAlphaNumeric1 && char1.match(whitespaceRegex_);
var whitespace2 = nonAlphaNumeric2 && char2.match(whitespaceRegex_);
var lineBreak1 = whitespace1 && char1.match(linebreakRegex_);
var lineBreak2 = whitespace2 && char2.match(linebreakRegex_);
var blankLine1 = lineBreak1 && one.match(blanklineEndRegex_);
var blankLine2 = lineBreak2 && two.match(blanklineStartRegex_);
if (blankLine1 || blankLine2) {
// Five points for blank lines.
return 5;
} else if (lineBreak1 || lineBreak2) {
// Four points for line breaks.
return 4;
} else if (nonAlphaNumeric1 && !whitespace1 && whitespace2) {
// Three points for end of sentences.
return 3;
} else if (whitespace1 || whitespace2) {
// Two points for whitespace.
return 2;
} else if (nonAlphaNumeric1 || nonAlphaNumeric2) {
// One point for non-alphanumeric.
return 1;
}
return 0;
}
var pointer = 1;
// Intentionally ignore the first and last element (don't need checking).
while (pointer < diffs.length - 1) {
if (
diffs[pointer - 1][0] == DIFF_EQUAL &&
diffs[pointer + 1][0] == DIFF_EQUAL
) {
// This is a single edit surrounded by equalities.
var equality1 = diffs[pointer - 1][1];
var edit = diffs[pointer][1];
var equality2 = diffs[pointer + 1][1];
// First, shift the edit as far left as possible.
var commonOffset = diff_commonSuffix(equality1, edit);
if (commonOffset) {
var commonString = edit.substring(edit.length - commonOffset);
equality1 = equality1.substring(0, equality1.length - commonOffset);
edit = commonString + edit.substring(0, edit.length - commonOffset);
equality2 = commonString + equality2;
}
// Second, step character by character right, looking for the best fit.
var bestEquality1 = equality1;
var bestEdit = edit;
var bestEquality2 = equality2;
var bestScore =
diff_cleanupSemanticScore_(equality1, edit) +
diff_cleanupSemanticScore_(edit, equality2);
while (edit.charAt(0) === equality2.charAt(0)) {
equality1 += edit.charAt(0);
edit = edit.substring(1) + equality2.charAt(0);
equality2 = equality2.substring(1);
var score =
diff_cleanupSemanticScore_(equality1, edit) +
diff_cleanupSemanticScore_(edit, equality2);
// The >= encourages trailing rather than leading whitespace on edits.
if (score >= bestScore) {
bestScore = score;
bestEquality1 = equality1;
bestEdit = edit;
bestEquality2 = equality2;
}
}
if (diffs[pointer - 1][1] != bestEquality1) {
// We have an improvement, save it back to the diff.
if (bestEquality1) {
diffs[pointer - 1][1] = bestEquality1;
} else {
diffs.splice(pointer - 1, 1);
pointer--;
}
diffs[pointer][1] = bestEdit;
if (bestEquality2) {
diffs[pointer + 1][1] = bestEquality2;
} else {
diffs.splice(pointer + 1, 1);
pointer--;
}
}
}
pointer++;
}
}
/**
* Reorder and merge like edit sections. Merge equalities.

@@ -489,8 +819,8 @@ * Any edit section can move as long as it doesn't cross an equality.

function diff_cleanupMerge(diffs, fix_unicode) {
diffs.push([DIFF_EQUAL, '']); // Add a dummy entry at the end.
diffs.push([DIFF_EQUAL, ""]); // Add a dummy entry at the end.
var pointer = 0;
var count_delete = 0;
var count_insert = 0;
var text_delete = '';
var text_insert = '';
var text_delete = "";
var text_insert = "";
var commonlength;

@@ -504,3 +834,2 @@ while (pointer < diffs.length) {

case DIFF_INSERT:
count_insert++;

@@ -528,5 +857,11 @@ text_insert += diffs[pointer][1];

// and we keep scanning for the next equality before rewriting the tuples.
if (previous_equality >= 0 && ends_with_pair_start(diffs[previous_equality][1])) {
if (
previous_equality >= 0 &&
ends_with_pair_start(diffs[previous_equality][1])
) {
var stray = diffs[previous_equality][1].slice(-1);
diffs[previous_equality][1] = diffs[previous_equality][1].slice(0, -1);
diffs[previous_equality][1] = diffs[previous_equality][1].slice(
0,
-1
);
text_delete = stray + text_delete;

@@ -571,5 +906,11 @@ text_insert = stray + text_insert;

if (previous_equality >= 0) {
diffs[previous_equality][1] += text_insert.substring(0, commonlength);
diffs[previous_equality][1] += text_insert.substring(
0,
commonlength
);
} else {
diffs.splice(0, 0, [DIFF_EQUAL, text_insert.substring(0, commonlength)]);
diffs.splice(0, 0, [
DIFF_EQUAL,
text_insert.substring(0, commonlength),
]);
pointer++;

@@ -584,5 +925,12 @@ }

diffs[pointer][1] =
text_insert.substring(text_insert.length - commonlength) + diffs[pointer][1];
text_insert = text_insert.substring(0, text_insert.length - commonlength);
text_delete = text_delete.substring(0, text_delete.length - commonlength);
text_insert.substring(text_insert.length - commonlength) +
diffs[pointer][1];
text_insert = text_insert.substring(
0,
text_insert.length - commonlength
);
text_delete = text_delete.substring(
0,
text_delete.length - commonlength
);
}

@@ -602,3 +950,8 @@ }

} else {
diffs.splice(pointer - n, n, [DIFF_DELETE, text_delete], [DIFF_INSERT, text_insert]);
diffs.splice(
pointer - n,
n,
[DIFF_DELETE, text_delete],
[DIFF_INSERT, text_insert]
);
pointer = pointer - n + 2;

@@ -616,9 +969,9 @@ }

count_delete = 0;
text_delete = '';
text_insert = '';
text_delete = "";
text_insert = "";
break;
}
}
if (diffs[diffs.length - 1][1] === '') {
diffs.pop(); // Remove the dummy entry at the end.
if (diffs[diffs.length - 1][1] === "") {
diffs.pop(); // Remove the dummy entry at the end.
}

@@ -633,16 +986,26 @@

while (pointer < diffs.length - 1) {
if (diffs[pointer - 1][0] === DIFF_EQUAL &&
diffs[pointer + 1][0] === DIFF_EQUAL) {
if (
diffs[pointer - 1][0] === DIFF_EQUAL &&
diffs[pointer + 1][0] === DIFF_EQUAL
) {
// This is a single edit surrounded by equalities.
if (diffs[pointer][1].substring(diffs[pointer][1].length -
diffs[pointer - 1][1].length) === diffs[pointer - 1][1]) {
if (
diffs[pointer][1].substring(
diffs[pointer][1].length - diffs[pointer - 1][1].length
) === diffs[pointer - 1][1]
) {
// Shift the edit over the previous equality.
diffs[pointer][1] = diffs[pointer - 1][1] +
diffs[pointer][1].substring(0, diffs[pointer][1].length -
diffs[pointer - 1][1].length);
diffs[pointer][1] =
diffs[pointer - 1][1] +
diffs[pointer][1].substring(
0,
diffs[pointer][1].length - diffs[pointer - 1][1].length
);
diffs[pointer + 1][1] = diffs[pointer - 1][1] + diffs[pointer + 1][1];
diffs.splice(pointer - 1, 1);
changes = true;
} else if (diffs[pointer][1].substring(0, diffs[pointer + 1][1].length) ==
diffs[pointer + 1][1]) {
} else if (
diffs[pointer][1].substring(0, diffs[pointer + 1][1].length) ==
diffs[pointer + 1][1]
) {
// Shift the edit over the next equality.

@@ -663,10 +1026,10 @@ diffs[pointer - 1][1] += diffs[pointer + 1][1];

}
};
}
function is_surrogate_pair_start(charCode) {
return charCode >= 0xD800 && charCode <= 0xDBFF;
return charCode >= 0xd800 && charCode <= 0xdbff;
}
function is_surrogate_pair_end(charCode) {
return charCode >= 0xDC00 && charCode <= 0xDFFF;
return charCode >= 0xdc00 && charCode <= 0xdfff;
}

@@ -700,3 +1063,3 @@

[DIFF_INSERT, newMiddle],
[DIFF_EQUAL, after]
[DIFF_EQUAL, after],
]);

@@ -707,6 +1070,7 @@ }

// note: this runs after equality check has ruled out exact equality
var oldRange = typeof cursor_pos === 'number' ?
{ index: cursor_pos, length: 0 } : cursor_pos.oldRange;
var newRange = typeof cursor_pos === 'number' ?
null : cursor_pos.newRange;
var oldRange =
typeof cursor_pos === "number"
? { index: cursor_pos, length: 0 }
: cursor_pos.oldRange;
var newRange = typeof cursor_pos === "number" ? null : cursor_pos.newRange;
// take into account the old and new selection to generate the best diff

@@ -794,6 +1158,6 @@ // possible for a text edit. for example, a text change from "xxx" to "xx"

function diff(text1, text2, cursor_pos) {
function diff(text1, text2, cursor_pos, cleanup) {
// only pass fix_unicode=true at the top level, not when diff_main is
// recursively invoked
return diff_main(text1, text2, cursor_pos, true);
return diff_main(text1, text2, cursor_pos, cleanup, true);
}

@@ -800,0 +1164,0 @@

{
"name": "fast-diff",
"version": "1.2.0",
"version": "1.3.0",
"description": "Fast Javascript text diff",

@@ -8,5 +8,9 @@ "author": "Jason Chen <jhchen7@gmail.com>",

"types": "diff.d.ts",
"files": [
"diff.d.ts"
],
"devDependencies": {
"lodash": "~3.9.3",
"seedrandom": "~2.4.0"
"lodash": "~4.17.21",
"nyc": "~15.1.0",
"seedrandom": "~3.0.5"
},

@@ -21,3 +25,3 @@ "repository": {

"scripts": {
"test": "node test.js"
"test": "nyc node test.js"
},

@@ -24,0 +28,0 @@ "license": "Apache-2.0",

@@ -1,2 +0,2 @@

# Fast Diff [![Build Status](https://travis-ci.org/jhchen/fast-diff.svg)](https://travis-ci.org/jhchen/fast-diff)
# Fast Diff ![Build Status](https://github.com/jhchen/fast-diff/actions/workflows/test.yml/badge.svg)

@@ -3,0 +3,0 @@ This is a simplified import of the excellent [diff-match-patch](https://code.google.com/p/google-diff-match-patch/) library by [Neil Fraser](https://neil.fraser.name/) into the Node.js environment. The match and patch parts are removed, as well as all the extra diff options. What remains is incredibly fast diffing between two strings.

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