internal NumericMappingEntry ParseSingleMappingSegment()

in src/SourcemapToolkit.SourcemapParser/MappingListParser.cs [142:196]
27 lines of code
7 McCabe index (conditional complexity)

		internal NumericMappingEntry ParseSingleMappingSegment(IReadOnlyList<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;
		}