Scripting Flash apps: scanning the input file

term papers on divorce Here we go. I know that probably I should have started this new topic talking about the grammar of the language we are going to implement, but as long as I see grammar strictly related to parsing, I’ve preferred to talk about http://basilsdentalclinic.com/?international-finance-assignment-help international finance assignment help scanning first.

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term paper cover We will go back to the grammar the next time, when talking about how to parse an input file.

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writing a literature review dissertation I wrote about scanning (or http://bluntmax.com/how-to-write-a-easy-essay/ how to write a easy essay lexing if you prefer) a while ago, when blogging about expression evalution in ActionScript. Scanning an input file is quite always the same (although some languages might require unusual features), and what I wrote about expressions works also for a general language.

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customer service representative essays The goal of the scanning process is to group some characters together, skipping the ones that have no meaning for the language like spaces. Each group of characters is usually called http://eaglesviewinc.org/last-minute-homework-help/ last minute homework help token. So a http://rest-cor.org/?write-an-essay-about-jealousy write an essay about jealousy Scanner converts a textual input into a stream of tokens, each one rappresenting a possible valid word for our language. While scanning you don’t take care about the meaning of what you are grouping or about the fact that a sequence of tokens is meaningful. This is a task for the http://www.hospitaldelsur.gov.co/?essays-about-sports essays about sports Parser as we will see.

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e learning thesis master When talking about expressions, I showed a manual implementation for a Lexer. Now I want to take a different approach and show you a possible implementation for a simple dynamic scanner. This scanner will be based on regular expressions: each regular expression will rappresent a given token, and we will be able to assign callbacks to the scanner that will be executed each time a given token is extracted from the input.
Writing a general and reusable scanner is usually a good practice. A common approach is to use some http://gbciconnect.com/college-application-essay-writing/ college application essay writing scanner generators, that are usually regular expression based too but are able to generate the code for a scanner at compile time. Our approach is different (and generates slower scanners) because regular expressions are evaluated at runtime; but it is fine for a test project.

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http://www.rieticultura.net/?application-essay-writing-service application essay writing service You can download the source code for the regular expression based lexer (RegexLexer) http://n5xmotorsport.com/?buy-cheap-articles-online buy cheap articles online here, as long as a simple usage example. Let’s see this example together so we can briefly discuss it (PBLexer.as):

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