-
Notifications
You must be signed in to change notification settings - Fork 72
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
feat(patterns): pattern-based compression
- Loading branch information
Showing
8 changed files
with
1,327 additions
and
171 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,292 @@ | ||
| // @ts-check | ||
| import { assertChecker, makeTagged, passStyleOf } from '@endo/marshal'; | ||
| import { recordNames, recordValues } from '@endo/marshal/src/encodePassable.js'; | ||
|
|
||
| import { | ||
| kindOf, | ||
| assertPattern, | ||
| maybeMatchHelper, | ||
| matches, | ||
| checkMatches, | ||
| mustMatch, | ||
| } from './patternMatchers.js'; | ||
| import { isKey } from '../keys/checkKey.js'; | ||
| import { keyEQ } from '../keys/compareKeys.js'; | ||
|
|
||
| /** @typedef {import('@endo/pass-style').Passable} Passable */ | ||
| /** @typedef {import('../types.js').Compress} Compress */ | ||
| /** @typedef {import('../types.js').MustCompress} MustCompress */ | ||
| /** @typedef {import('../types.js').Decompress} Decompress */ | ||
| /** @typedef {import('../types.js').MustDecompress} MustDecompress */ | ||
| /** @typedef {import('../types.js').Pattern} Pattern */ | ||
|
|
||
| const { fromEntries } = Object; | ||
| const { Fail, quote: q } = assert; | ||
|
|
||
| const isNonCompressingMatcher = pattern => { | ||
| const patternKind = kindOf(pattern); | ||
| if (patternKind === undefined) { | ||
| return false; | ||
| } | ||
| const matchHelper = maybeMatchHelper(patternKind); | ||
| return matchHelper && matchHelper.compress === undefined; | ||
| }; | ||
|
|
||
| /** | ||
| * When, for example, all the specimens in a given store match a | ||
| * specific pattern, then each of those specimens must contain the same | ||
| * literal superstructure as their one shared pattern. Therefore, storing | ||
| * that literal superstructure would be redumdant. If `specimen` does | ||
| * match `pattern`, then `compress(specimen, pattern)` will return a bindings | ||
| * array which is hopefully more compact than `specimen` as a whole, but | ||
| * carries all the information from specimen that cannot be derived just | ||
| * from knowledge that it matches this `pattern`. | ||
| * | ||
| * @type {Compress} | ||
| */ | ||
| const compress = (specimen, pattern) => { | ||
| if (isNonCompressingMatcher(pattern)) { | ||
| if (matches(specimen, pattern)) { | ||
| return harden({ compressed: specimen }); | ||
| } | ||
| return undefined; | ||
| } | ||
|
|
||
| // Not yet frozen! Used to accumulate bindings | ||
| const bindings = []; | ||
| const emitBinding = binding => { | ||
| bindings.push(binding); | ||
| }; | ||
| harden(emitBinding); | ||
|
|
||
| /** | ||
| * @param {Passable} innerSpecimen | ||
| * @param {Pattern} innerPattern | ||
| * @returns {boolean} | ||
| */ | ||
| const compressRecur = (innerSpecimen, innerPattern) => { | ||
| assertPattern(innerPattern); | ||
| if (isKey(innerPattern)) { | ||
| return keyEQ(innerSpecimen, innerPattern); | ||
| } | ||
| const patternKind = kindOf(innerPattern); | ||
| const specimenKind = kindOf(innerSpecimen); | ||
| switch (patternKind) { | ||
| case undefined: { | ||
| return false; | ||
| } | ||
| case 'copyArray': { | ||
| if ( | ||
| specimenKind !== 'copyArray' || | ||
| innerSpecimen.length !== innerPattern.length | ||
| ) { | ||
| return false; | ||
| } | ||
| return innerPattern.every((p, i) => compressRecur(innerSpecimen[i], p)); | ||
| } | ||
| case 'copyRecord': { | ||
| if (specimenKind !== 'copyRecord') { | ||
| return false; | ||
| } | ||
| const specimenNames = recordNames(innerSpecimen); | ||
| const pattNames = recordNames(innerPattern); | ||
|
|
||
| if (specimenNames.length !== pattNames.length) { | ||
| return false; | ||
| } | ||
| const specimenValues = recordValues(innerSpecimen, specimenNames); | ||
| const pattValues = recordValues(innerPattern, pattNames); | ||
|
|
||
| return pattNames.every( | ||
| (name, i) => | ||
| specimenNames[i] === name && | ||
| compressRecur(specimenValues[i], pattValues[i]), | ||
| ); | ||
| } | ||
| case 'copyMap': { | ||
| if (specimenKind !== 'copyMap') { | ||
| return false; | ||
| } | ||
| const { | ||
| payload: { keys: pattKeys, values: valuePatts }, | ||
| } = innerPattern; | ||
| const { | ||
| payload: { keys: specimenKeys, values: specimenValues }, | ||
| } = innerSpecimen; | ||
| // TODO BUG: this assumes that the keys appear in the | ||
| // same order, so we can compare values in that order. | ||
| // However, we're only guaranteed that they appear in | ||
| // the same rankOrder. Thus we must search one of these | ||
| // in the other's rankOrder. | ||
| if (!keyEQ(specimenKeys, pattKeys)) { | ||
| return false; | ||
| } | ||
| return compressRecur(specimenValues, valuePatts); | ||
| } | ||
| default: | ||
| { | ||
| const matchHelper = maybeMatchHelper(patternKind); | ||
| if (matchHelper) { | ||
| if (matchHelper.compress) { | ||
| const subCompressedRecord = matchHelper.compress( | ||
| innerSpecimen, | ||
| innerPattern.payload, | ||
| compress, | ||
| ); | ||
| if (subCompressedRecord === undefined) { | ||
| return false; | ||
| } else { | ||
| emitBinding(subCompressedRecord.compressed); | ||
| return true; | ||
| } | ||
| } else if (matches(innerSpecimen, innerPattern)) { | ||
| assert(isNonCompressingMatcher(innerPattern)); | ||
| emitBinding(innerSpecimen); | ||
| return true; | ||
| } else { | ||
| return false; | ||
| } | ||
| } | ||
| } | ||
| throw Fail`unrecognized kind: ${q(patternKind)}`; | ||
| } | ||
| }; | ||
|
|
||
| if (compressRecur(specimen, pattern)) { | ||
| return harden({ compressed: bindings }); | ||
| } else { | ||
| return undefined; | ||
| } | ||
| }; | ||
| harden(compress); | ||
|
|
||
| /** | ||
| * `mustCompress` is to `compress` approximately as `fit` is to `matches`. | ||
| * Where `compress` indicates pattern match failure by returning `undefined`, | ||
| * `mustCompress` indicates pattern match failure by throwing an error | ||
| * with a good pattern-match-failure diagnostic. Thus, like `fit`, | ||
| * `mustCompress` has an additional optional `label` parameter to be used on | ||
| * the outside of that diagnostic if needed. If `mustCompress` does return | ||
| * normally, then the pattern match succeeded and `mustCompress` returns a | ||
| * valid compressed value. | ||
| * | ||
| * @type {MustCompress} | ||
| */ | ||
| export const mustCompress = (specimen, pattern, label = undefined) => { | ||
| const compressedRecord = compress(specimen, pattern); | ||
| if (compressedRecord !== undefined) { | ||
| return compressedRecord.compressed; | ||
| } | ||
| // `compress` is validating, so we don't need to redo all of `mustMatch`. | ||
| // We use it only to generate the error. | ||
| // Should only throw | ||
| checkMatches(specimen, pattern, assertChecker, label); | ||
| throw Fail`internal: ${label}: inconsistent pattern match: ${q(pattern)}`; | ||
| }; | ||
| harden(mustCompress); | ||
|
|
||
| /** | ||
| * `decompress` reverses the compression performed by `compress` | ||
| * or `mustCompress`, in order to recover the equivalent | ||
| * of the original specimen from the `bindings` array and the `pattern`. | ||
| * | ||
| * @type {Decompress} | ||
| */ | ||
| const decompress = (compressed, pattern) => { | ||
| if (isNonCompressingMatcher(pattern)) { | ||
| return compressed; | ||
| } | ||
|
|
||
| assert(Array.isArray(compressed)); | ||
| passStyleOf(compressed) === 'copyArray' || | ||
| Fail`Pattern ${pattern} expected bindings array: ${compressed}`; | ||
| let i = 0; | ||
| const takeBinding = () => { | ||
| i < compressed.length || | ||
| Fail`Pattern ${q(pattern)} expects more than ${q( | ||
| compressed.length, | ||
| )} bindings: ${compressed}`; | ||
| const binding = compressed[i]; | ||
| i += 1; | ||
| return binding; | ||
| }; | ||
| harden(takeBinding); | ||
|
|
||
| const decompressRecur = innerPattern => { | ||
| assertPattern(innerPattern); | ||
| if (isKey(innerPattern)) { | ||
| return innerPattern; | ||
| } | ||
| const patternKind = kindOf(innerPattern); | ||
| switch (patternKind) { | ||
| case undefined: { | ||
| throw Fail`decompress expected a pattern: ${q(innerPattern)}`; | ||
| } | ||
| case 'copyArray': { | ||
| return harden(innerPattern.map(p => decompressRecur(p))); | ||
| } | ||
| case 'copyRecord': { | ||
| const pattNames = recordNames(innerPattern); | ||
| const pattValues = recordValues(innerPattern, pattNames); | ||
| const entries = pattNames.map((name, j) => [ | ||
| name, | ||
| decompressRecur(pattValues[j]), | ||
| ]); | ||
| // Reverse so printed form looks less surprising, | ||
| // with ascenting rather than descending property names. | ||
| return harden(fromEntries(entries.reverse())); | ||
| } | ||
| case 'copyMap': { | ||
| const { | ||
| payload: { keys: pattKeys, values: valuePatts }, | ||
| } = innerPattern; | ||
| return makeTagged( | ||
| 'copyMap', | ||
| harden({ | ||
| keys: pattKeys, | ||
| values: valuePatts.map(p => decompressRecur(p)), | ||
| }), | ||
| ); | ||
| } | ||
| default: | ||
| { | ||
| const matchHelper = maybeMatchHelper(patternKind); | ||
| if (matchHelper) { | ||
| if (matchHelper.decompress) { | ||
| const subCompressed = takeBinding(); | ||
| return matchHelper.decompress( | ||
| subCompressed, | ||
| innerPattern.payload, | ||
| decompress, | ||
| ); | ||
| } else { | ||
| assert(isNonCompressingMatcher(innerPattern)); | ||
| return takeBinding(); | ||
| } | ||
| } | ||
| } | ||
| throw Fail`unrecognized pattern kind: ${q(patternKind)} ${q( | ||
| innerPattern, | ||
| )}`; | ||
| } | ||
| }; | ||
|
|
||
| return decompressRecur(pattern); | ||
| }; | ||
| harden(decompress); | ||
|
|
||
| /** | ||
| * `decompress` reverses the compression performed by `compress` | ||
| * or `mustCompress`, in order to recover the equivalent | ||
| * of the original specimen from `compressed` and `pattern`. | ||
| * | ||
| * @type {MustDecompress} | ||
| */ | ||
| export const mustDecompress = (compressed, pattern, label = undefined) => { | ||
| const value = decompress(compressed, pattern); | ||
| // `decompress` does some checking, but is not validating, so we | ||
| // need to do the full `mustMatch` here to validate as well as to generate | ||
| // the error if invalid. | ||
| mustMatch(value, pattern, label); | ||
| return value; | ||
| }; |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Oops, something went wrong.