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Move textSpan and textChangeRange impls to the compiler layer.

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This commit is contained in:
Cyrus Najmabadi
2014-12-10 14:36:37 -08:00
parent c2d4cd5887
commit 888b88ee43
6 changed files with 232 additions and 316 deletions
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2
src/services/services.ts
View File

@@ -1613,7 +1613,7 @@ module ts {
public getChangeRange(filename: string, lastKnownVersion: string, oldScriptSnapshot: IScriptSnapshot): TextChangeRange {
var currentVersion = this.getVersion(filename);
if (lastKnownVersion === currentVersion) {
return TextChangeRangeObject.unchanged; // "No changes"
return unchangedTextChangeRange; // "No changes"
}
var scriptSnapshot = this.getScriptSnapshot(filename);

2
src/services/shims.ts
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@@ -328,7 +328,7 @@ module ts {
}
var decoded: { span: { start: number; length: number; }; newLength: number; } = JSON.parse(encoded);
return new TextChangeRangeObject(
return createTextChangeRange(
createTextSpan(decoded.span.start, decoded.span.length), decoded.newLength);
}
}

162
src/services/text.ts
View File

@@ -1,164 +1,2 @@
module ts {
export class TextChangeRangeObject implements TextChangeRange {
public static unchanged = new TextChangeRangeObject(createTextSpan(0, 0), 0);
private _span: TextSpan;
private _newLength: number;
/**
* Initializes a new instance of TextChangeRange.
*/
constructor(span: TextSpan, newLength: number) {
Debug.assert(newLength >= 0, "newLength");
this._span = span;
this._newLength = newLength;
}
/**
* The span of text before the edit which is being changed
*/
public span(): TextSpan {
return this._span;
}
/**
* Width of the span after the edit. A 0 here would represent a delete
*/
public newLength(): number {
return this._newLength;
}
public newSpan(): TextSpan {
return createTextSpan(this.span().start(), this.newLength());
}
public isUnchanged(): boolean {
return this.span().isEmpty() && this.newLength() === 0;
}
/**
* Called to merge all the changes that occurred across several versions of a script snapshot
* into a single change. i.e. if a user keeps making successive edits to a script we will
* have a text change from V1 to V2, V2 to V3, ..., Vn.
*
* This function will then merge those changes into a single change range valid between V1 and
* Vn.
*/
public static collapseChangesAcrossMultipleVersions(changes: TextChangeRange[]): TextChangeRange {
if (changes.length === 0) {
return TextChangeRangeObject.unchanged;
}
if (changes.length === 1) {
return changes[0];
}
// We change from talking about { { oldStart, oldLength }, newLength } to { oldStart, oldEnd, newEnd }
// as it makes things much easier to reason about.
var change0 = changes[0];
var oldStartN = change0.span().start();
var oldEndN = change0.span().end();
var newEndN = oldStartN + change0.newLength();
for (var i = 1; i < changes.length; i++) {
var nextChange = changes[i];
// Consider the following case:
// i.e. two edits. The first represents the text change range { { 10, 50 }, 30 }. i.e. The span starting
// at 10, with length 50 is reduced to length 30. The second represents the text change range { { 30, 30 }, 40 }.
// i.e. the span starting at 30 with length 30 is increased to length 40.
//
// 0 10 20 30 40 50 60 70 80 90 100
// -------------------------------------------------------------------------------------------------------
// | /
// | /----
// T1 | /----
// | /----
// | /----
// -------------------------------------------------------------------------------------------------------
// | \
// | \
// T2 | \
// | \
// | \
// -------------------------------------------------------------------------------------------------------
//
// Merging these turns out to not be too difficult. First, determining the new start of the change is trivial
// it's just the min of the old and new starts. i.e.:
//
// 0 10 20 30 40 50 60 70 80 90 100
// ------------------------------------------------------------*------------------------------------------
// | /
// | /----
// T1 | /----
// | /----
// | /----
// ----------------------------------------$-------------------$------------------------------------------
// . | \
// . | \
// T2 . | \
// . | \
// . | \
// ----------------------------------------------------------------------*--------------------------------
//
// (Note the dots represent the newly inferrred start.
// Determining the new and old end is also pretty simple. Basically it boils down to paying attention to the
// absolute positions at the asterixes, and the relative change between the dollar signs. Basically, we see
// which if the two $'s precedes the other, and we move that one forward until they line up. in this case that
// means:
//
// 0 10 20 30 40 50 60 70 80 90 100
// --------------------------------------------------------------------------------*----------------------
// | /
// | /----
// T1 | /----
// | /----
// | /----
// ------------------------------------------------------------$------------------------------------------
// . | \
// . | \
// T2 . | \
// . | \
// . | \
// ----------------------------------------------------------------------*--------------------------------
//
// In other words (in this case), we're recognizing that the second edit happened after where the first edit
// ended with a delta of 20 characters (60 - 40). Thus, if we go back in time to where the first edit started
// that's the same as if we started at char 80 instead of 60.
//
// As it so happens, the same logic applies if the second edit precedes the first edit. In that case rahter
// than pusing the first edit forward to match the second, we'll push the second edit forward to match the
// first.
//
// In this case that means we have { oldStart: 10, oldEnd: 80, newEnd: 70 } or, in TextChangeRange
// semantics: { { start: 10, length: 70 }, newLength: 60 }
//
// The math then works out as follows.
// If we have { oldStart1, oldEnd1, newEnd1 } and { oldStart2, oldEnd2, newEnd2 } then we can compute the
// final result like so:
//
// {
// oldStart3: Min(oldStart1, oldStart2),
// oldEnd3 : Max(oldEnd1, oldEnd1 + (oldEnd2 - newEnd1)),
// newEnd3 : Max(newEnd2, newEnd2 + (newEnd1 - oldEnd2))
// }
var oldStart1 = oldStartN;
var oldEnd1 = oldEndN;
var newEnd1 = newEndN;
var oldStart2 = nextChange.span().start();
var oldEnd2 = nextChange.span().end();
var newEnd2 = oldStart2 + nextChange.newLength();
oldStartN = Math.min(oldStart1, oldStart2);
oldEndN = Math.max(oldEnd1, oldEnd1 + (oldEnd2 - newEnd1));
newEndN = Math.max(newEnd2, newEnd2 + (newEnd1 - oldEnd2));
}
return new TextChangeRangeObject(createTextSpanFromBounds(oldStartN, oldEndN), /*newLength: */newEndN - oldStartN);
}
}
}