Lexical Error Compiler Construction
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Lexical Errors In Compiler Design
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Lexical Error Example
takes a minute: Sign up What is an example of a lexical error and is it possible that a language has no lexical errors? up vote 7 down vote favorite 3 for our compiler theory class, we are tasked with lexical phase errors in compiler design creating a simple interpreter for our own designed programming language. I am using jflex and cup as my generators but i'm a bit stuck with what a lexical error is. Also, is it recommended that i use the state feature of jflex? it feels wrong as it seems like the parser is better suited to handling that aspect. and do you recommend any other tools to create the language. I'm sorry if i'm impatient but it's due on tuesday. compiler-theory lexical phase errors in compiler design ppt jflex share|improve this question asked Aug 14 '10 at 18:57 cesar 2,414103052 add a comment| 4 Answers 4 active oldest votes up vote 11 down vote accepted A lexical error is any input that can be rejected by the lexer. This generally results from token recognition falling off the end of the rules you've defined. For example (in no particular syntax): [0-9]+ ===> NUMBER token [a-zA-Z] ===> LETTERS token anything else ===> error! If you think about a lexer as a finite state machine that accepts valid input strings, then errors are going to be any input strings that do not result in that finite state machine reaching an accepting state. The rest of your question was rather unclear to me. If you already have some tools you are using, then perhaps you're best to learn how to achieve what you want to achieve using those tools (I have no experience with either of the tools you mentioned). EDIT: Having re-read your question, there's a second part I can answer. It is possible that a language could have no lexical errors - it's the language in which any input string at all is valid input. share|improve this answer edited Aug 15 '10 at 17:34 answered Aug 14 '10 at 23:41 Gian 10.9k3043 add a comment| Did you find this question interesting? Try our newsletter Sign up for our newsletter and get our top new questions delivered to your inbox (
Design - Architecture Compiler Design - Phases of Compiler Compiler Design - Lexical Analysis Compiler - Regular Expressions Compiler Design - Finite Automata Compiler Design - Syntax Analysis Compiler
Lexical Phase Errors In Compiler Design Pdf
Design - Types of Parsing Compiler Design - Top-Down Parser Compiler Design example of lexical error in compiler design - Bottom-Up Parser Compiler Design - Error Recovery Compiler Design - Semantic Analysis Compiler - Run-time Environment Compiler
Lexical Error In English
Design - Symbol Table Compiler - Intermediate Code Compiler Design - Code Generation Compiler Design - Code Optimization Compiler Design Useful Resources Compiler Design - Quick Guide Compiler Design - http://stackoverflow.com/questions/3484689/what-is-an-example-of-a-lexical-error-and-is-it-possible-that-a-language-has-no Useful Resources Compiler Design - Discussion Selected Reading Developer's Best Practices Questions and Answers Effective Resume Writing HR Interview Questions Computer Glossary Who is Who Compiler Design - Error Recovery Advertisements Previous Page Next Page A parser should be able to detect and report any error in the program. It is expected that when an error is encountered, the parser https://www.tutorialspoint.com/compiler_design/compiler_design_error_recovery.htm should be able to handle it and carry on parsing the rest of the input. Mostly it is expected from the parser to check for errors but errors may be encountered at various stages of the compilation process. A program may have the following kinds of errors at various stages: Lexical : name of some identifier typed incorrectly Syntactical : missing semicolon or unbalanced parenthesis Semantical : incompatible value assignment Logical : code not reachable, infinite loop There are four common error-recovery strategies that can be implemented in the parser to deal with errors in the code. Panic mode When a parser encounters an error anywhere in the statement, it ignores the rest of the statement by not processing input from erroneous input to delimiter, such as semi-colon. This is the easiest way of error-recovery and also, it prevents the parser from developing infinite loops. Statement mode When a parser encounters an error, it tries to take corrective measures so that the rest of inputs of statement allow the parser to parse ahead. For example, inserting a missing semicolon, replacing comm
Επιλέξτε τη γλώσσα σας. Κλείσιμο Μάθετε περισσότερα View this message in English Το YouTube εμφανίζεται στα Ελληνικά. Μπορείτε να αλλάξετε https://www.youtube.com/watch?v=uXllgXORZx0 αυτή την προτίμηση παρακάτω. Learn more http://www.pling.org.uk/cs/lsa.html You're viewing YouTube in Greek. You can change this preference below. Κλείσιμο Ναι, θέλω να τη κρατήσω Αναίρεση Κλείσιμο Αυτό το βίντεο δεν είναι διαθέσιμο. Ουρά παρακολούθησηςΟυράΟυρά lexical error παρακολούθησηςΟυρά Κατάργηση όλωνΑποσύνδεση Φόρτωση... Ουρά παρακολούθησης Ουρά __count__/__total__ Lexical Analysis Lex Lexical Errors | Syntax Error on Token Examples | Recognition of Tokens Gate Instructors ΕγγραφήΕγγραφήκατεΚατάργηση εγγραφής20.53520 χιλ. Φόρτωση... Φόρτωση... Σε λειτουργία... Προσθήκη σε... Θέλετε in compiler design να το δείτε ξανά αργότερα; Συνδεθείτε για να προσθέσετε το βίντεο σε playlist. Σύνδεση Κοινή χρήση Περισσότερα Αναφορά Θέλετε να αναφέρετε το βίντεο; Συνδεθείτε για να αναφέρετε ακατάλληλο περιεχόμενο. Σύνδεση Στατιστικά στοιχεία 3.334 προβολές 8 Σας αρέσει αυτό το βίντεο; Συνδεθείτε για να μετρήσει η άποψή σας. Σύνδεση 9 0 Δεν σας αρέσει αυτό το βίντεο; Συνδεθείτε για να μετρήσει η άποψή σας. Σύνδεση 1 Φόρτωση... Φόρτωση... Φόρτωση... Η δυνατότητα αξιολόγησης είναι διαθέσιμη όταν το βίντεο είναι ενοικιασμένο. Αυτή η λειτουργία δεν είναι διαθέσιμη αυτήν τη στιγμή. Δοκιμάστε ξανά αργότερα. Δημοσιεύτηκε στις 17 Αυγ 2015Lexical Analysis Lex | Lex
Sheffield 2009-10. They are published here in case others find them useful, but I provide no warranty for their accuracy, completeness or whether or not they are up-to-date. The contents of this page have dubious copyright status, as great portions of some of my revision notes are verbatim from the lecture slides, what the lecturer wrote on the board, or what they said. Additionally, lots of the images have been captured from the lecture slides. Languages For more detailsee TOC. Languages are a potentially infinite set of strings (sometimes called sentences, which are a sequence of symbols from a given alphabet). The tokens of each sentence are ordered according to some structure. A grammar is a set of rules that describe a language. Grammars assign structure to a sentence. An automaton is an algorithm that can recognise (accept) all sentences of a language and reject those which do not belong to it. Lexical and syntactical analysis can be simplified to a machine that takes in some program code, and then returns syntax errors, parse trees and data structures. We can think of the process of description transformation, where we take some source description, apply a transformation technique and end up with a target description - this is inference mapping between two equivalent languages, where the destination is a machine executable. Compilers are an important part of computer science, even if you never write a compiler, as the concepts are used regularly, in interpreters, intelligent editors, source code debugging, natural language processing (e.g., for AI) and for things such as XML. Throughout the years, progress has been made in the field of programming to bring higher and higher levels of abstraction, moving from machine code, to assembler, to high level langauges and now to object orrientation, reusable languages and virtual machines. Translation Process LSA only deals with the front-end of the comp