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What are the possible error recovery actions in lexical Analyzer?
Wiki User
∙ 13y ago
• Not too many types of lexical errors
- Illegal character
- Ill-formed constant
• How is it handled?
- Discard and print a message
- BUT:
• If a character in the middle of a lexeme is wrong, do you
discard the char or the whole lexeme?
• Try to correct
Wiki User
∙ 13y ago
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Describe how lexical analyzer generators are used to translate regular expressions into deterministic finite automata?
Lexical analyzer generators translate regular expressions (the lexical analyzer definition) into finite automata (the lexical analyzer). For example, a lexical analyzer definition may specify a number of regular expressions describing different lexical forms (integer, string, identifier, comment, etc.). The lexical analyzer generator would then translate that definition into a program module that can use the deterministic finite automata to analyze text and split it into lexemes (tokens).
What is a program for lexical analyzer in c?
lex for example.
What are the functions of lexical analyzer?
The lexical analyzer function, named after rule declarations, recognizes tokens from the input stream and returns them to the parser.
1. What are three reasons why syntax analyzers are based on grammars?
Simplicity-Techniques for lexical analysis are less complex than those required for syntax analysis, so the lexical-analysis process can be sim- pler if it is separate. Also, removing the low-level details of lexical analy- sis from the syntax analyzer makes the syntax analyzer both smaller and less complex.Efficiency-Although it pays to optimize the lexical analyzer, because lexical analysis requires a significant portion of total compilation time, it is not fruitful to optimize the syntax analyzer. Separation facilitates this selective optimization.Portability-Because the lexical analyzer reads input program files and often includes buffering of that input, it is somewhat platform dependent. However, the syntax analyzer can be platform independent. It is always good to isolate machine-dependent parts of any software system.
What is lexical analysis?
A compiler is usually divided into different phases. The input to the compiler is the source program and the output is a target program. Lexical analyzer is the first phase of a compiler which gets source program as input. It scans the source program from left to right and produces tokens as output. A token can be seen as a sequence of characters having a collective meaning. Lexical analyzer also called by names like scanner, linear analyzer etc.
Describe how lexical analyzer generators are used to translate regular expressions into deterministic finite automata?
Lexical analyzer generators translate regular expressions (the lexical analyzer definition) into finite automata (the lexical analyzer). For example, a lexical analyzer definition may specify a number of regular expressions describing different lexical forms (integer, string, identifier, comment, etc.). The lexical analyzer generator would then translate that definition into a program module that can use the deterministic finite automata to analyze text and split it into lexemes (tokens).
What is a program for lexical analyzer in c?
lex for example.
What are the functions of lexical analyzer?
The lexical analyzer function, named after rule declarations, recognizes tokens from the input stream and returns them to the parser.
1. What are three reasons why syntax analyzers are based on grammars?
Simplicity-Techniques for lexical analysis are less complex than those required for syntax analysis, so the lexical-analysis process can be sim- pler if it is separate. Also, removing the low-level details of lexical analy- sis from the syntax analyzer makes the syntax analyzer both smaller and less complex.Efficiency-Although it pays to optimize the lexical analyzer, because lexical analysis requires a significant portion of total compilation time, it is not fruitful to optimize the syntax analyzer. Separation facilitates this selective optimization.Portability-Because the lexical analyzer reads input program files and often includes buffering of that input, it is somewhat platform dependent. However, the syntax analyzer can be platform independent. It is always good to isolate machine-dependent parts of any software system.
What is lexical analysis?
A compiler is usually divided into different phases. The input to the compiler is the source program and the output is a target program. Lexical analyzer is the first phase of a compiler which gets source program as input. It scans the source program from left to right and produces tokens as output. A token can be seen as a sequence of characters having a collective meaning. Lexical analyzer also called by names like scanner, linear analyzer etc.
What is the application of regular expression in compiler construction?
Regular Expression is another way of implementing a lexical analyzer or scanner.
Why lexical analyzer known as scanner?
lexical analysis involves scanning the program to be compiled and recognizing the tokens that make up the source statements .Scanners are usually designed to recognize keywords ,operators,and identifiers as well as integers,floating point numbers,character strings etc.....so they are known as scanners
The language like 'c' allows the use of same name for two different variables Is it possible for lexical analyser to distinguish between such variables?
Using the same name for two different variables in languages like C is possible only within two different scopes, such as outside a block and inside a block... int somevariable; /* outside scope */ { ... int somevariable; /* inside scope */ } In order for a lexical analyzer to distinguish those two variables, it must be able to parse the program and resolve scope the same way the compiler does.
Importance of lexical verb in sentences?
A lexical verb is the main verb of the sentence. All verbs include a lexical verb. A lexical verb does not require an auxiliary verb, but an auxiliary verb exists only to help a lexical verb. It cannot exist alone. A lexical verb is a verb that provides information. The opposite of lexical verbs are auxiliary verbs, which provide grammatical structure. Lexical verbs are an open class type of verb and are used to express states and actions. Such verbs are also known as main verbs. The main role of the lexical verb is to be the main verb of the sentence. The verb provides the reader or listener with key information linking the subject and the object. While many auxiliary verbs can also be main verbs, lexical verbs such as "play," "paint" and "record" stand out because they give very specific information and are always the lexical verb. Haseen ur Rehman
What is a sentence for lexical?
His lexical skills were far better than anyone in the company. This is an example of word for lexical. The instructor defended throwing a book at me to wake me up by saying that he was using a lexical approach.
What is lexical awareness?
Lexical awareness = knowledge of vocabulary (word meanings)
What is a lexical verb?
A lexical verb is simply the main verb in a sentence.
