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Make stream parser resilient to text in streams #1215

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f775a85
Make Stream Parse ignore words that contain 'stream'
andrew-trefethen Apr 16, 2022
db3e875
Test that the stream parser ignore words containing 'stream'
andrew-trefethen Apr 16, 2022
0e7f44b
Conform to linter rules
andrew-trefethen Apr 16, 2022
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15 changes: 14 additions & 1 deletion src/core/parser/PDFObjectParser.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -243,23 +243,36 @@ class PDFObjectParser extends BaseParser {

protected findEndOfStreamFallback(startPos: Position) {
// Move to end of stream, while handling nested streams
let acceptUnprefixedStream = true;
let nestingLvl = 1;
let end = this.bytes.offset();

while (!this.bytes.done()) {
end = this.bytes.offset();

if (this.matchKeyword(Keywords.stream)) {
if (
this.matchKeyword(Keywords.embeddedStream1) ||
this.matchKeyword(Keywords.embeddedStream2) ||
this.matchKeyword(Keywords.embeddedStream3) ||
this.matchKeyword(Keywords.embeddedStream4) ||
this.matchKeyword(Keywords.embeddedStream5) ||
this.matchKeyword(Keywords.embeddedStream6) ||
this.matchKeyword(Keywords.embeddedStream7) ||
(acceptUnprefixedStream && this.matchKeyword(Keywords.stream))
) {
nestingLvl += 1;
acceptUnprefixedStream = true;
} else if (
this.matchKeyword(Keywords.EOF1endstream) ||
this.matchKeyword(Keywords.EOF2endstream) ||
this.matchKeyword(Keywords.EOF3endstream) ||
this.matchKeyword(Keywords.endstream)
) {
nestingLvl -= 1;
acceptUnprefixedStream = true;
} else {
this.bytes.next();
acceptUnprefixedStream = false;
}

if (nestingLvl === 0) break;
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17 changes: 16 additions & 1 deletion src/core/syntax/Keywords.ts
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Original file line number Diff line number Diff line change
@@ -1,6 +1,14 @@
import CharCodes from 'src/core/syntax/CharCodes';

const { Space, CarriageReturn, Newline } = CharCodes;
const {
Space,
CarriageReturn,
Newline,
Tab,
LessThan,
GreaterThan,
BackSlash,
} = CharCodes;

const stream = [
CharCodes.s,
Expand Down Expand Up @@ -76,6 +84,13 @@ export const Keywords = {
streamEOF2: [...stream, CarriageReturn, Newline],
streamEOF3: [...stream, CarriageReturn],
streamEOF4: [...stream, Newline],
embeddedStream1: [Tab, ...stream],
embeddedStream2: [Space, ...stream],
embeddedStream3: [CarriageReturn, ...stream],
embeddedStream4: [Newline, ...stream],
embeddedStream5: [LessThan, ...stream],
embeddedStream6: [GreaterThan, ...stream],
embeddedStream7: [BackSlash, ...stream],
endstream,
EOF1endstream: [CarriageReturn, Newline, ...endstream],
EOF2endstream: [CarriageReturn, ...endstream],
Expand Down
4 changes: 4 additions & 0 deletions tests/core/parser/PDFObjectParser.spec.ts
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Expand Up @@ -576,6 +576,10 @@ describe(`PDFObjectParser`, () => {
'<<>>\n\rstream\n\rthingz\n\rendstream',
'<<\n/Length 8\n>>\nstream\n\rthingz\n\nendstream',
],
[
'<<>>\n\rstream\n\rthingz bitstream\n\rendstream',
'<<\n/Length 18\n>>\nstream\n\rthingz bitstream\n\nendstream',
],
].forEach(([input, output]) => {
it(`can parse ${JSON.stringify(input)}`, () => {
const object = parse(typedArrayFor(input));
Expand Down