/// <summary>
/// Top level API that should be called for decoding the MappingsString element. It will convert the string containing Base64
/// VLQ encoded segments into a list of MappingEntries.
/// </summary>
internal List <MappingEntry> ParseMappings(string mappingString, List <string> names, List <string> sources)
{
List <MappingEntry> mappingEntries = new List <MappingEntry>();
MappingsParserState currentMappingsParserState = new MappingsParserState();
// The V3 source map format calls for all Base64 VLQ segments to be seperated by commas.
// Each line of generated code is separated using semicolons. The count of semicolons encountered gives the current line number.
string[] lines = mappingString.Split(';');
for (int lineNumber = 0; lineNumber < lines.Length; lineNumber += 1)
{
// The only value that resets when encountering a semicolon is the starting column.
currentMappingsParserState = new MappingsParserState(currentMappingsParserState, newGeneratedLineNumber: lineNumber, newGeneratedColumnBase: 0);
string[] segmentsForLine = lines[lineNumber].Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
foreach (string segment in segmentsForLine)
{
NumericMappingEntry numericMappingEntry = ParseSingleMappingSegment(Base64VlqDecoder.Decode(segment), currentMappingsParserState);
mappingEntries.Add(numericMappingEntry.ToMappingEntry(names, sources));
// Update the current MappingParserState based on the generated MappingEntry
currentMappingsParserState = new MappingsParserState(currentMappingsParserState,
newGeneratedColumnBase: numericMappingEntry.GeneratedColumnNumber,
newSourcesListIndexBase: numericMappingEntry.OriginalSourceFileIndex,
newOriginalSourceStartingLineBase: numericMappingEntry.OriginalLineNumber,
newOriginalSourceStartingColumnBase: numericMappingEntry.OriginalColumnNumber,
newNamesListIndexBase: numericMappingEntry.OriginalNameIndex);
}
}
return(mappingEntries);
}
/// <summary>
/// Parses a single "segment" of the mapping field for a source map. A segment describes one piece of code in the generated source.
/// In the mapping string "AAaAA,CAACC;", AAaAA and CAACC are both segments. This method assumes the segments have already been decoded
/// from Base64 VLQ into a list of integers.
/// </summary>
/// <param name="segmentFields">The integer values for the segment fields</param>
/// <param name="mappingsParserState">The current state of the state variables for the parser</param>
/// <returns></returns>
internal NumericMappingEntry ParseSingleMappingSegment(List <int> segmentFields, MappingsParserState mappingsParserState)
{
if (segmentFields == null)
{
throw new ArgumentNullException(nameof(segmentFields));
}
if (segmentFields.Count == 0 || segmentFields.Count == 2 || segmentFields.Count == 3)
{
throw new ArgumentOutOfRangeException(nameof(segmentFields));
}
NumericMappingEntry numericMappingEntry = new NumericMappingEntry
{
GeneratedLineNumber = mappingsParserState.CurrentGeneratedLineNumber,
GeneratedColumnNumber = mappingsParserState.CurrentGeneratedColumnBase + segmentFields[0]
};
/*
* The following description was taken from the Sourcemap V3 spec https://docs.google.com/document/d/1U1RGAehQwRypUTovF1KRlpiOFze0b-_2gc6fAH0KY0k/mobilebasic?pref=2&pli=1
* The Sourcemap V3 spec is under a Creative Commons Attribution-ShareAlike 3.0 Unported License. https://creativecommons.org/licenses/by-sa/3.0/
*
* Each VLQ segment has 1, 4, or 5 variable length fields.
* The fields in each segment are:
* 1. The zero-based starting column of the line in the generated code that the segment represents.
* If this is the first field of the first segment, or the first segment following a new generated line(“;”),
* then this field holds the whole base 64 VLQ.Otherwise, this field contains a base 64 VLQ that is relative to
* the previous occurrence of this field.Note that this is different than the fields below because the previous
* value is reset after every generated line.
* 2. If present, an zero - based index into the “sources” list.This field is a base 64 VLQ relative to the previous
* occurrence of this field, unless this is the first occurrence of this field, in which case the whole value is represented.
* 3. If present, the zero-based starting line in the original source represented. This field is a base 64 VLQ relative to the
* previous occurrence of this field, unless this is the first occurrence of this field, in which case the whole value is
* represented.Always present if there is a source field.
* 4. If present, the zero - based starting column of the line in the source represented.This field is a base 64 VLQ relative to
* the previous occurrence of this field, unless this is the first occurrence of this field, in which case the whole value is
* represented.Always present if there is a source field.
* 5. If present, the zero - based index into the “names” list associated with this segment.This field is a base 64 VLQ relative
* to the previous occurrence of this field, unless this is the first occurrence of this field, in which case the whole value
* is represented.
*/
if (segmentFields.Count > 1)
{
numericMappingEntry.OriginalSourceFileIndex = mappingsParserState.SourcesListIndexBase + segmentFields[1];
numericMappingEntry.OriginalLineNumber = mappingsParserState.OriginalSourceStartingLineBase + segmentFields[2];
numericMappingEntry.OriginalColumnNumber = mappingsParserState.OriginalSourceStartingColumnBase + segmentFields[3];
}
if (segmentFields.Count >= 5)
{
numericMappingEntry.OriginalNameIndex = mappingsParserState.NamesListIndexBase + segmentFields[4];
}
return(numericMappingEntry);
}