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Merged
takikawa merged 2 commits into from
Nov 14, 2025
Merged

Range mappings: refactor decoding out of mapping decoding #235

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e4912a3
Refactor range mapping decoding based on feedback
takikawa Nov 13, 2025
5b20f97
Continue if mapping is NOT-FOUND in range mapping update
takikawa Nov 14, 2025
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84 changes: 50 additions & 34 deletions spec.emu
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Original file line number Diff line number Diff line change
Expand Up @@ -684,9 +684,10 @@
1. Let _ignoreListField_ be GetOptionalListOfArrayIndexes(_json_, *"ignoreList"*).
1. Let _sources_ be DecodeSourceMapSources(_baseURL_, _sourceRootField_, _sourcesField_, _sourcesContentField_, _ignoreListField_).
1. Let _namesField_ be GetOptionalListOfStrings(_json_, *"names"*).
1. Let _mappings_ be DecodeMappings(_mappingsField_, _namesField_, _sources_).
1. <ins>Let _rangeMappingsField_ be GetOptionalString(_json_, *"rangeMappings"*).</ins>
1. <ins>Let _rangeMappings_ be DecodeRangeMappings(_rangeMappingsField_).</ins>
1. Let _mappings_ be DecodeMappings(_mappingsField_, _namesField_, _sources_, <ins>_rangeMappings_</ins>).
1. <ins>Perform UpdateMappingsForRangeMappings(_mappings_, _rangeMappings_).</ins>
1. [declared="a,b"] Sort _mappings_ in ascending order, with a Decoded Mapping Record _a_ being less than a Decoded Mapping Record _b_ if ComparePositions(_a_.[[GeneratedPosition]], _b_.[[GeneratedPosition]]) is ~lesser~.
1. Return the Decoded Source Map Record { [[File]]: _fileField_, [[Sources]]: _sources_, [[Mappings]]: _mappings_ }.
</emu-alg>
Expand Down Expand Up @@ -921,10 +922,6 @@
<td>[[NameIndex]]</td>
<td>a non-negative integer</td>
</tr>
<tr>
<td><ins>[[MappingIndex]]</ins></td>
<td><ins>a non-negative integer</ins></td>
</tr>
</table>
</emu-table>

Expand All @@ -935,7 +932,6 @@
_mappings_: a List of Decoded Mapping Records,
_names_: a List of Strings,
_sources_: a List of Decoded Source Records,
<ins>_rangeMappings_: a List of of Decoded Range Mapping Offset Records,</ins>
)
</h1>
<dl class="header"></dl>
Expand All @@ -944,11 +940,10 @@
Line `;` LineList
</emu-grammar>
<emu-alg>
1. Perform DecodeMappingsField of |Line| with arguments _state_, _mappings_, _names_<ins>,</ins> <del>and</del> _sources_ <ins>and _rangeMappings_</ins>.
1. Perform DecodeMappingsField of |Line| with arguments _state_, _mappings_, _names_ and _sources_.
1. Set _state_.[[GeneratedLine]] to _state_.[[GeneratedLine]] + 1.
1. Set _state_.[[GeneratedColumn]] to 0.
1. <ins>Set _state_.[[MappingIndex]] to 0.</ins>
1. Perform DecodeMappingsField of |LineList| with arguments _state_, _mappings_, _names_<ins>,</ins> <del>and</del> _sources_ <ins>and _rangeMappings_</ins>.
1. Perform DecodeMappingsField of |LineList| with arguments _state_, _mappings_, _names_ and _sources_.
</emu-alg>
<emu-grammar>
Line : [empty]
Expand All @@ -961,50 +956,47 @@
Mapping `,` MappingList
</emu-grammar>
<emu-alg>
1. Perform DecodeMappingsField of |Mapping| with arguments _state_, _mappings_, _names_<ins>,</ins> <del>and</del> _sources_ <ins>and _rangeMappings_</ins>.
1. Perform DecodeMappingsField of |MappingList| with arguments _state_, _mappings_, _names_<ins>,</ins> <del>and</del> _sources_ <ins>and _rangeMappings_</ins>.
1. Perform DecodeMappingsField of |Mapping| with arguments _state_, _mappings_, _names_ and _sources_.
1. Perform DecodeMappingsField of |MappingList| with arguments _state_, _mappings_, _names_ and _sources_.
</emu-alg>
<emu-grammar>
Mapping :
GeneratedColumn
</emu-grammar>
<emu-alg>
1. Perform DecodeMappingsField of |GeneratedColumn| with arguments _state_, _mappings_, _names_<ins>,</ins> <del>and</del> _sources_ <ins>and _rangeMappings_</ins>.
1. Perform DecodeMappingsField of |GeneratedColumn| with arguments _state_, _mappings_, _names_ and _sources_.
1. If _state_.[[GeneratedColumn]] &lt; 0, then
1. Optionally report an error.
1. Return.
1. Let _position_ be a new Position Record { [[Line]]: _state_.[[GeneratedLine]], [[Column]]: _state_.[[GeneratedColumn]] }.
1. Let _decodedMapping_ be a new DecodedMappingRecord { [[GeneratedPosition]]: _position_, [[OriginalPosition]]: *null*, [[Name]]: *null*, <ins>[[IsRangeMapping]]: *false*</ins> }.
1. Append _decodedMapping_ to _mappings_.
1. <ins>Set _state_.[[MappingIndex]] to _state_.[[MappingIndex]] + 1.</ins>
</emu-alg>
<emu-grammar>
Mapping :
GeneratedColumn OriginalSource OriginalLine OriginalColumn Name?
</emu-grammar>
<emu-alg>
1. Perform DecodeMappingsField of |GeneratedColumn| with arguments _state_, _mappings_, _names_<ins>,</ins> <del>and</del> _sources_ <ins>and _rangeMappings_</ins>.
1. Perform DecodeMappingsField of |GeneratedColumn| with arguments _state_, _mappings_, _names_ and _sources_.
1. If _state_.[[GeneratedColumn]] &lt; 0, then
1. Optionally report an error.
1. Return.
1. Let _generatedPosition_ be a new Position Record { [[Line]]: _state_.[[GeneratedLine]], [[Column]]: _state_.[[GeneratedColumn]] }.
1. Perform DecodeMappingsField of |OriginalSource| with arguments _state_, _mappings_, _names_<ins>,</ins> <del>and</del> _sources_ <ins>and _rangeMappings_</ins>.
1. Perform DecodeMappingsField of |OriginalLine| with arguments _state_, _mappings_, _names_<ins>,</ins> <del>and</del> _sources_ <ins>and _rangeMappings_</ins>.
1. Perform DecodeMappingsField of |OriginalColumn| with arguments _state_, _mappings_, _names_<ins>,</ins> <del>and</del> _sources_ <ins>and _rangeMappings_</ins>.
1. Perform DecodeMappingsField of |OriginalSource| with arguments _state_, _mappings_, _names_ and _sources_.
1. Perform DecodeMappingsField of |OriginalLine| with arguments _state_, _mappings_, _names_ and _sources_.
1. Perform DecodeMappingsField of |OriginalColumn| with arguments _state_, _mappings_, _names_ and _sources_.
1. If _state_.[[SourceIndex]] &lt; 0 or _state_.[[SourceIndex]] ≥ the number of elements of _sources_ or _state_.[[OriginalLine]] &lt; 0 or _state_.[[OriginalColumn]] &lt; 0, then
1. Optionally report an error.
1. Let _originalPosition_ be *null*.
1. Else,
1. Let _originalPosition_ be a new Original Position Record { [[Source]]: _sources_[_state_.[[SourceIndex]]], [[Line]]: _state_.[[OriginalLine]], [[Column]]: _state_.[[OriginalColumn]] }.
1. Let _name_ be *null*.
1. If |Name| is present, then
1. Perform DecodeMappingsField of |Name| with arguments _state_, _mappings_, _names_<ins>,</ins> <del>and</del> _sources_ <ins>and _rangeMappings_</ins>.
1. Perform DecodeMappingsField of |Name| with arguments _state_, _mappings_, _names_ and _sources_.
1. If _state_.[[NameIndex]] &lt; 0 or _state_.[[NameIndex]] ≥ the number of elements of _names_, optionally report an error.
1. Else, set _name_ to _names_[_state_.[[NameIndex]]].
1. <ins>Let _isRangeMapping_ be the result of performing LookupRangeMapping with arguments _rangeMappings_, _state_.[[GeneratedLine]], and _state_.[[MappingIndex]].</ins>
1. Let _decodedMapping_ be a new DecodedMappingRecord { [[GeneratedPosition]]: _generatedPosition_, [[OriginalPosition]]: _originalPosition_, [[Name]]: _name_, <ins>[[IsRangeMapping]]: _isRangeMapping_</ins> }.
1. Let _decodedMapping_ be a new DecodedMappingRecord { [[GeneratedPosition]]: _generatedPosition_, [[OriginalPosition]]: _originalPosition_, [[Name]]: _name_, <ins>[[IsRangeMapping]]: *false*</ins> }.
1. Append _decodedMapping_ to _mappings_.
1. <ins>Set _state_.[[MappingIndex]] to _state_.[[MappingIndex]] + 1.</ins>
</emu-alg>
<emu-grammar>
GeneratedColumn :
Expand Down Expand Up @@ -1055,7 +1047,6 @@
_rawMappings_: a String,
_names_: a List of Strings,
_sources_: a List of Decoded Source Records,
<ins>_rangeMappings_: a List of Decoded Range Mapping Offset Records,</ins>
): a List of Decoded Mapping Record
</h1>
<dl class="header"></dl>
Expand All @@ -1066,7 +1057,7 @@
1. Optionally report an error.
1. Return _mappings_.
1. Let _state_ be a new Decode Mapping State Record with all fields set to 0.
1. Perform DecodeMappingsField of _mappingsNode_ with arguments _state_, _mappings_, _names_<ins>,</ins> <del>and</del> _sources_ <ins>and _rangeMappings_</ins>.
1. Perform DecodeMappingsField of _mappingsNode_ with arguments _state_, _mappings_, _names_ and _sources_.
1. Return _mappings_.
</emu-alg>
</emu-clause>
Expand Down Expand Up @@ -1255,21 +1246,46 @@
</emu-alg>
</emu-clause>

<emu-clause id="sec-LookupRangeMapping" type="abstract operation">
<emu-clause id="sec-UpdateMappingsForRangeMapping" type="abstract operation">
<h1>
LookupRangeMapping (
_rangeMappings_: a List of Decoded Range Mapping Offset Records,
_generatedLine_: an integral Number,
_mappingIndex_: an integral Number,
): a Boolean
UpdateMappingsForRangeMappings (
_mappings_: a List of Decoded Mapping Records,
_rangeMappingsOffsets_: a List of Decoded Range Mapping Offset Records,
): ~unused~
</h1>
<dl class="header"></dl>
<emu-alg>
1. Let _rangeMappingOffset_ be a new Decoded Range Mapping Offset Record { [[GeneratedLine]] : _generatedLine_, [[MappingIndex]]: _mappingIndex_ }.
1. If _rangeMappingOffset_ is an element of _rangeMappings_, then
1. Return *true*.
1. Else,
1. Return *false*.
1. For each Decoded Range Mapping Offset Record _rangeMappingOffset_ of _rangeMappingsOffsets_, do
1. Let _mapping_ be the result of FindMappingForRangeMappingOffset(_mappings_, _rangeMappingOffset_).
1. If _mapping_ is ~not-found~, then
1. Optionally report an error.
1. Else,
1. If _mapping_.[[OriginalPosition]] is *null*, optionally report an error.
1. Assert: _mapping_.[[IsRangeMapping]] is *false*.
1. Set _mapping_.[[IsRangeMapping]] to *true*.
</emu-alg>
</emu-clause>

<emu-clause id="sec-FindMappingForRangeMappingOffset" type="abstract operation">
<h1>
FindMappingForRangeMappingOffset (
_mappings_: a List of Decoded Mapping Records,
_offset_: a Decoded Range Mapping Offset Record,
): a Decoded Mapping Record or ~not-found~
</h1>
<dl class="header"></dl>
<emu-alg>
1. Let _currentLine_ be *null*.
1. Let _currentIndex_ be 0.
1. For each Decoded Mapping Record _mapping_ of _mappings_, do
1. If _currentLine_ ≠ _mapping_.[[GeneratedLine]], then
1. Set _currentLine_ to _mapping_.[[GeneratedLine]].
1. Set _currentIndex_ to 0.
1. Else,
1. Set _currentIndex_ to _currentIndex_ + 1.
1. If _currentLine_ = _offset_.[[GeneratedLine]] and _currentIndex_ = _offset_.[[MappingIndex]], then
1. Return _mapping_.
1. Return ~not-found~.
</emu-alg>
</emu-clause>
</emu-clause>
Expand Down