Dave Jarvis' Repositories

Author	DaveJarvis <email>
Date	2020-09-12 13:24:22 GMT-0700
Commit	20bb20d51146136896105b4594769e0282e90a62
Parent	d5bc5ae
Delta	27 lines added, 10 lines removed, 17-line increase

src/main/java/com/scrivenvar/processors/math/MathProcessor.java

		* Responsible for parsing equations in a document and rendering them as
		* scalable vector graphics (SVG).
		+ * <p>
		+ * This class is not thread-safe due to the reuse of an internal buffer to
		+ * prevent memory reallocations on subsequent runs of the processor.
		+ * </p>
		*/
		public class MathProcessor extends AbstractProcessor<String> {

		* Compiled regular expression for matching math expression.
		*/
		- public static final Pattern REGEX_PATTERN = compile( REGEX );
		+ private static final Pattern REGEX_PATTERN = compile( REGEX );

		private static final int GROUP_DELIMITED = 2;

		- private final float mSize = 20f;
		+ private static final float mSize = 20f;
		+
		+ /**
		+ * Reduces number of memory reallocations as formulas are added or removed
		+ * on subsequent calls to {@link #apply(String)}. This only shaves a few
		+ * milliseconds off the total time.
		+ */
		+ private final StringBuilder mBuffer = new StringBuilder( 65535 );
		+
		private final TeXFont mTeXFont = new DefaultTeXFont( mSize );
		private final TeXEnvironment mEnvironment = new TeXEnvironment( mTeXFont );
		private final SvgGraphics2D mGraphics = new SvgGraphics2D();

		public MathProcessor( final Processor<String> successor ) {
		super( successor );
		mGraphics.scale( mSize, mSize );
		}

		+ /**
		+ * This method only takes a few seconds to generate
		+ *
		+ * @param s The string containing zero or more math formula bracketed by
		+ * dollar symbols.
		+ * @return The given string with all formulas transformed to SVG format.
		+ */
		@Override
		public String apply( final String s ) {
		- final var result = new StringBuilder( s.length() * 2 );
		-
		+ final var matcher = REGEX_PATTERN.matcher( s );
		int index = 0;

		- final var matcher = REGEX_PATTERN.matcher( s );
		+ // Wipe out previous data, but don't deallocate previous memory.
		+ mBuffer.setLength( 0 );

		while( matcher.find() ) {

		box.draw( mGraphics, layout.getX(), layout.getY() );

		- result.append( s, index, matcher.start() );
		- result.append( mGraphics );
		+ mBuffer.append( s, index, matcher.start() );
		+ mBuffer.append( mGraphics );
		index = matcher.end();
		}
		-
		- result.append( s, index, s.length() );

		- return result.toString();
		+ return mBuffer.append( s, index, s.length() ).toString();
		}
		}

Minor optimization of formula generation