Lexical Analyzer In C
Write A C Program To Simulate Lexical Analyzer For Validating Operators
Program for Lexical Analyzer in C. Very simple lexical analyzer which reads source code from file and then generate tokens. LexicalAnalyzer.cpp. Program for Lexical Analyzer in C. Very simple lexical analyzer which reads source code from file and then generate tokens. LexicalAnalyzer.cpp.
There are multiple ways of tokenizing a stream of characters. Just like there are LL Recursive-Descent Parsers there are LL Recursive-Descent Lexers. These tokenizers analyze the character stream one by one, using multiple levels of lookahead in order to identity what token is currently being examined. However as this is our first foray into tokenizing I want to put off LL Recursive-Descent algorithms for now and use a very simple yet inefficient method.
Meet the Regex TokenizerThe great thing about regex is that it is trivial to match complex patterns and against specific tokens. This algorithm is very memory inefficient but considering that LQL queries are pretty small it doesn't really impact us. What is great is that it is super simple. How the algorithm worksWe create a list of regex patterns and associate each one to a token. Then we iterate through the query text character by character checking if the text at the current location matches a pattern.
Download delphi visual studio plugins. If it does then we create the token, create a new string cutting out the match text and continue checking. If it doesn't match then we create a new string cutting out the current character and do the check again and so on.It is inefficient as we generate multiple strings, each one slightly smaller than the one before.
This method would not be viable on very large texts (if you care about performance and load). TokenDefinition, TokenMatch and DslToken classes.