Sakurai/pdf.js
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Pattern match optimization

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notmasteryet 2011-09-23 20:59:07 -05:00
parent 502f7cb81b
commit eca6c82bbc
1 changed files with 14 additions and 11 deletions
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pdf.js
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@ -3176,23 +3176,26 @@ var XRef = (function xRefXRef() {
} }
function skipUntil(data, offset, what) { function skipUntil(data, offset, what) {
var length = what.length, dataLength = data.length; var length = what.length, dataLength = data.length;
var bytes = new Uint8Array(length); var skipped = 0;
var i, skipped = 0;
for (i = 0; i < length; i++)
bytes[i] = what.charCodeAt(i);
// finding byte sequence // finding byte sequence
while(offset < dataLength) { while (offset < dataLength) {
var i = 0; var i = 0;
while (i < length && data[offset + i] == bytes[i]) while (i < length && data[offset + i] == what[i])
++i; ++i;
if (i >= length) if (i >= length)
break; // sequnce found break; // sequence found
offset++; offset++;
skipped++; skipped++;
} }
return skipped; return skipped;
} }
var trailerBytes = new Uint8Array([116, 114, 97, 105, 108, 101, 114]);
var startxrefBytes = new Uint8Array([115, 116, 97, 114, 116, 120, 114,
101, 102]);
var endobjBytes = new Uint8Array([101, 110, 100, 111, 98, 106]);
var xrefBytes = new Uint8Array([47, 88, 82, 101, 102]);
var stream = this.stream; var stream = this.stream;
stream.pos = 0; stream.pos = 0;
var buffer = stream.getBytes(); var buffer = stream.getBytes();
@ -3216,9 +3219,9 @@ var XRef = (function xRefXRef() {
var token = readToken(buffer, position); var token = readToken(buffer, position);
var m; var m;
if (token === 'xref') { if (token === 'xref') {
position += skipUntil(buffer, position, 'trailer'); position += skipUntil(buffer, position, trailerBytes);
trailers.push(position); trailers.push(position);
position += skipUntil(buffer, position, 'startxref'); position += skipUntil(buffer, position, startxrefBytes);
} else if ((m = /^(\d+)\s+(\d+)\s+obj\b/.exec(token))) { } else if ((m = /^(\d+)\s+(\d+)\s+obj\b/.exec(token))) {
this.entries[m[1]] = { this.entries[m[1]] = {
offset: position, offset: position,
@ -3226,12 +3229,12 @@ var XRef = (function xRefXRef() {
uncompressed: true uncompressed: true
}; };
var contentLength = skipUntil(buffer, position, 'endobj') + 7; var contentLength = skipUntil(buffer, position, endobjBytes) + 7;
var content = buffer.subarray(position, position + contentLength); var content = buffer.subarray(position, position + contentLength);
// checking XRef stream suspect // checking XRef stream suspect
// (it shall have '/XRef' and next char is not a letter) // (it shall have '/XRef' and next char is not a letter)
var xrefTagOffset = skipUntil(content, 0, '/XRef'); var xrefTagOffset = skipUntil(content, 0, xrefBytes);
if (xrefTagOffset < contentLength && if (xrefTagOffset < contentLength &&
content[xrefTagOffset + 5] < 64) { content[xrefTagOffset + 5] < 64) {
xrefStms.push(position); xrefStms.push(position);