January 2013
Intermediate to advanced
328 pages
8h 5m
English
Content preview from The Definitive ANTLR 4 Reference, 2nd Edition
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Unbuffered Character and Token Streams
Because ANTLR recognizers buffer up the entire input character stream and all input tokens by default, they can’t handle input files that are bigger than a computer’s memory and can’t handle infinite streams like socket connections. To overcome this, you can use unbuffered versions of the character and token streams, which keep just a small sliding window into the streams: UnbufferedCharStream and UnbufferedTokenStream.
As a demonstration, here’s a modification of the comma-separated-value grammar from Parsing Comma-Separated Values that sums the floating-point values in a two-column file:
| | /** Rows are two real numbers: |
| | 0.9962269825793676, 0.9224608616182103 |
| | 0.91673278673353, -0.6374985722530822 ... |
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