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Topic: Lexical analysis

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	Lexical analysis - Wikipedia, the free encyclopedia
		Lexical analysis is the processing of an input sequence of characters (such as the source code of a computer program) to produce, as output, a sequence of symbols called "lexical tokens", or just "tokens".
		The Lex programming tool and its compiler is designed to generate code for fast lexical analysers based on a formal description of the lexical syntax.
		It is not generally considered sufficient for applications with a complicated set of lexical rules and severe performance requirements; for instance, the GNU Compiler Collection uses hand-written lexers.
	en.wikipedia.org /wiki/Lexical_analysis (1105 words)

	NLP: The Symbolic Approach -- Lexical Analysis (Site not responding. Last check: 2007-11-06)
		Lexical analysis addresses the problem of breaking a determined stream of words into sentences that will be subject to subsequent processing.
		Most of lexical analysis is straight-forward and generally uninteresting, and is mostly used to derive the tense of the conjugation of the specific words in the text.
		The simplest model of lexical analysis is one in which all words are simply listed along with their lexical features: lexical analysis thus becomes a simple matter of table lookup.
	www.stanford.edu /~pdeng/NLP/symbolic3.htm (219 words)

	Lexicon (disambiguation) - Wikipedia, the free encyclopedia
		In the lexicon of a language, lexical words or nouns refer to things.
		Lexical analysis, the name given to the processing of an input sequence of input to produce, as output, a sequence of symbols called "lexical tokens".
		This is a disambiguation page: a list of articles associated with the same title.
	en.wikipedia.org /wiki/Lexical (184 words)

	Lexical analysis: the Lex library
		For example a lexical grammar for Eiffel will specify that Identifier is the token type whose specimens are sequences of one or more characters, of which the first must be a letter (lower-case or upper-case) and any subsequent one is a letter, a digit (0 to 9) or an underscore.
		A lexical analyzer is an object equipped with operations that enable it to read a text according to a known lexical grammar and to identify the text's successive tokens.
		An instance of LEXICAL is a lexical analyzer for a certain lexical grammar.
	docs.eiffel.com /eiffelstudio/libraries/lex/content (4603 words)

	Lexical Analysis - CMPSCI 187
		Lexical analysis refers to the process of transforming something written as a sequence of characters into a sequence of tokens.
		By performing lexical analysis, a program produces a sequence of tokens, which is a higher level input stream for subsequent processes, such as syntactic analysis and code generation.
		It is worth noting that lexical analysis can be stated in a rather formulaic manner when resorting to transition diagrams.
	www.cs.umass.edu /~utgoff/cs187/lectures/lexical-analysis.html (721 words)

	Analyses
		Lexical analysis is the most lightweight of the three analyses.
		Semantic analysis, unfortunately, is usually not incremental, since a change in one region of a file might potentially impact the analysis of code in any other region.
		Analysis results beyong lexing are not very useful to display while the user is actively typing, so we delay running the analysis on the assumption that a pause in typing indicates a logical time to run the analysis.Each of the three analyses each have customizable idle times that delay their execution.
	harmonia.cs.berkeley.edu /harmonia/projects/harmonia-mode/doc/analyses.html (606 words)

	Lexical Analysis (Site not responding. Last check: 2007-11-06)
		Lexical analysis is the act of forming "words" out of individual characters.
		One alternative for lexical analysis would be for programmers to build these finite automata by hand.
		ML-Lex is a UNIX program which takes a lexical specification input file and builds an SML structure implementing a lexical analyzer for that specification.
	www.cs.jhu.edu /~scott/cw/lectures/lexical-analysis.html (693 words)

	Lexical Analysis - Table of Contents (Site not responding. Last check: 2007-11-06)
		Comments are character sequences to be ignored, while basic symbols are character sequences that correspond to terminal symbols of the grammar defining the phrase structure of the input (see Context-Free Grammars and Parsing of Syntactic Analysis).
		Since certain lexical structures are common to many languages, Eli provides a library of definitions that can be invoked simply be giving their names.
		Complex lexical analysis problems may require modification of the behavior of the generated module; Chapter 6 discusses the possibilities.
	eli-project.sourceforge.net /elionline4.4/lex_toc.html (403 words)

	Scham Lexical Analysis (Site not responding. Last check: 2007-11-06)
		White space (space, backspace, tab, vertical tab, newline and carriage return) is significant only where it is required to delimit a token or is part of a value such as a string; it is discarded in all other cases.
		Any lexical token (string of characters between delimiters) that is not one of the other lexical types is considered to be a symbol.
		It must therefore be surrounded by delimiters to be recognized as the dot lexical token whereas the parentheses and single quote are recognized in any context.
	www.cs.ubc.ca /spider/flinn/docs/scham/lexical.html (990 words)

	Textbook Methods of Parsing in COBOL
		Lexical analysis examines successive characters to identify tokens -- atomic units of meaning such as keywords, variable names, and elements of punctuation.
		The output of lexical analysis is a stream of tokens.
		Semantic analysis examines the fragments identified by syntactical analysis and attaches meaning to them, meanwhile enforcing the rules of the language.
	home.swbell.net /mck9/cobol/tech/textbook.html (639 words)

	Lexical Analysis
		This is a necessary step in generating a lexical analyzer since there may be hundreds of states in the table for the tokens in a programming language.
		This has been an introduction to lexical analyzer generators and the process of converting from a regular expression to a minimal DFA, which is the lexical analyzer.
		There are several lexical analyzer generators on the market, making it unlikely that anyone except a compiler tool designer or student in a sadistic instructor's class would ever have to write one.
	www.cs.wpi.edu /~kal/courses/compilers/module1/lexanal.html (2816 words)

	Lexical Analysis - The Generated Lexical Analyzer Module (Site not responding. Last check: 2007-11-06)
		Because the lexical analyzer normally works directly in the source module's buffer, that solution requires a change in the relationship between the lexical analyzer and its environment.
		There are three distinct aspects of the relationship between the lexical analyzer and its environment, and each is dealt with in one section of this chapter.
		First we consider how the lexical analyzer selects the character sequence to be scanned, then we see how the lexical analyzer's attention can be switched, and finally how the classification results are reported.
	www.ics.mq.edu.au /~asloane/eli/elionline4.4/lex_6.html (1740 words)

	Lexical Analysis with ANTLR
		The syntax for specifying lexical structure is the same for lexers, parsers, and tree parsers.
		Suffixing a lexical rule reference with '!' forces the text matched by the invoked rule to be discarded (it will not appear in the text for the invoking rule).
		Lexical analyzers were all built by hand in the early days of compilers until DFAs took over as the scanner implementation of choice.
	www.antlr.org /doc/lexer.html (8210 words)

	Notation (Site not responding. Last check: 2007-11-06)
		The descriptions of lexical analysis and syntax use a modified BNF grammar notation.
		Even though the notation used is almost the same, there is a big difference between the meaning of lexical and syntactic definitions: a lexical definition operates on the individual characters of the input source, while a syntax definition operates on the stream of tokens generated by the lexical analysis.
		All uses of BNF in the next chapter (``Lexical Analysis'') are lexical definitions; uses in subsequent chapters are syntactic definitions.
	www.cs.pdx.edu /~xinhong/python_docs/ref/node3.html (307 words)

	CS 4304 - Compilers and Translators - Lexical Analysis (Site not responding. Last check: 2007-11-06)
		The lexical analyzer is the first component of a compiler and is responsible for the first stage of recognizing the top level elements of the program;
		The output from a lexical analyzer is a "tokenized" code which identifies the elements of the code with tags;
		The lexical analyzer is associated with the initial development of the symbol table.
	ei.cs.vt.edu /~cs4304/lexical.html (323 words)

	CS 321: Class Notes 2004/10/11
		When we get to syntax analysis, we will see that it is scrictly more powerful than lexical analysis...
		The easiest way to write a lexical analyzer is as a stream to stream model, remembering that historically memory was expensive, so compilers were not designed to remember the contents of the source files.
		In many cases the tokenizer is the slowest part of hte lexical analyzer because it is the only part of the program that has to look at every character of the source file.
	www.cs.pdx.edu /~cmay/class_notes/cs321/2004_10_11.html (763 words)

	Lexical Analysis.
		An important aspect of lexical analysis is the treatment of unknown words.
		In addition to the treatment of unknown words, the robustness of the system is enhanced by the possibility to skip tokens of the input.
		During lexical analysis, tags are optionally extended to include neighbouring words which are classified as `skipable'.
	odur.let.rug.nl /vannoord/papers/alpino/node9.html (348 words)

	RFC 822: Part 3: lexical Analysis of Tokens (Site not responding. Last check: 2007-11-06)
		Rather than obscuring the syntax specifications for these structured fields with explicit syntax for this linear-white-space, the existence of another "lexical" analyzer is assumed.
		When a comment acts as the delimiter between a sequence of two lexical symbols, such as two atoms, it is lex- ically equivalent with a single SPACE, for the purposes of regenerating the sequence, such as when passing the sequence onto a mail protocol server.
		(See the "Lexical Analysis of Messages" section on "Folding Long Header Fields" above, and the section on "Case Independence" below.) Note that the official semantics therefore do not "see" any unquoted CRLFs that are in comments, although particular pars- ing programs may wish to note their presence.
	www.w3.org /Protocols/rfc822/3_Lexical.html (2376 words)

	[Chapter 2] Lexical Analysis (Site not responding. Last check: 2007-11-06)
		This component is responsible for discovering higher levels of organization in the sequences of tokens discovered by lexical analysis.
		Java lexical analysis consists of two phases: pre-processing and tokenization.
		As always, ambiguities in lexical rules are resolved by matching the longest possible sequence of characters.
	www.serve.com /josh/books/java/langref/ch02_01.htm (852 words)

	Phase 1: Lexical Analysis
		What is expected for the source programs is given in the general description of the project; here we will more describe in detail the lexical analysis aspect of phase 1.
		In phase 1 you will implement two aspects of the lexical analyzer: the trace option as given in the compiler man page and error handling.
		If the token read is valid, no other action should be taken by the lexical analyzer at this stage except to return with a non-zero value.
	www.eecg.toronto.edu /~csc467/project/phase1.html (797 words)

	Lexical analysis and Java: Part 1
		The purpose of lexical analyzers is to take a stream of input characters and decode them into higher level tokens that a parser can understand.
		Parsers consume the output of the lexical analyzer and operate by analyzing the sequence of tokens returned.
		It is up to the application to decide what action to take when the parser identifies either an end state or an error state.
	www.javaworld.com /javaworld/jw-01-1997/jw-01-indepth.html (1335 words)

	Ruby Buzz Forum - How complex is your Ruby? Time for some lexical variability analysis
		I've been performing some lexical analysis on Ruby software to provide a first-order answer to those questions.
		The "lexical complexity" above represent the amount of information carried by a token (type) if we know the type of the token immediately preceding it.
		The case of rbconfig.rb is more interesting: there are 41 distinct token types, but the lexical variability is very low; in other words, the code is very repetitive.
	www.artima.com /forums/flat.jsp?forum=123&thread=141431 (497 words)

	E-MELD School of Best Practice: Lexical Analysis
		Data can be entered as individual lexical entries or in a paradigm worksheet
		The initial version of the FIELD tool was designed for Biao Min, a Hmong-Mien language, and is being expanded to accommodate the Guaicuruan language, Mocoví, and the Algonquian language Potawatomi.
		The entry interface is customized using your Language Profile: entry fields are created based on the profile's indication of the language's grammatical functions and feature values and your choice of gloss language, and the preferred format of example sentences and comparison forms.
	emeld.org /school/workroom/lexicon (507 words)

	D Programming Language - Lexical
		In D, the lexical analysis is independent of the syntax parsing and the semantic analysis.
		The D lexical grammar is designed to be suitable for high speed scanning, it has a minimum of special case rules, there is only one phase of translation, and to make it easy to write a correct scanner for.
		Special token sequences are processed by the lexical analyzer, may appear between any other tokens, and do not affect the syntax parsing.
	www.digitalmars.com /d/lex.html (1633 words)

	Linguistics tools
		When you complete the analysis process for a particular wordform-in-context, it displays the corresponding word and morpheme analyses in aligned interlinear format.
		Morphemes analyzed in the Analysis editor are automatically inserted as entries in the lexical database.
		The lexical database tools in LinguaLinks are based on generally accepted models for lexicography and semantics.
	www.ethnologue.com /LL_docs/LingTool.asp (338 words)

	Lexical Analysis:
		This handout gives a step-by-step process for building a lexical analysis program - a core component of a compiler.
		Lexical analysis identifies the tokens of a language.
		The job of a lexer is to read an input string and separate it into tokens from the input language.
	www.cs.utexas.edu /users/porter/cs304p/hw8.old.html (1411 words)

	[No title] (Site not responding. Last check: 2007-11-06)
		Its recommendations are clear, automatic text analysis should use weighted terms derived from document excerpts whose length is at least that of a document abstract.
		It is appears that all of those who courageously embark on the study in this area are already convinced that NLP and Text Analysis is and should be a science that can and will be solved.
		If you have read a little in this area as I have it is hard not to come to the conclusion that firstly there is nothing at all Natural about Natural Language Processing and secondly if it was so natural then one should ask the million-dollar questions.
	www.scism.sbu.ac.uk /inmandw/tutorials/irtutorials/P1.DOC (1230 words)

	Presentation -- Lexical analysis in source code scanning (Site not responding. Last check: 2007-11-06)
		many are based on lexical analysis, which matches patterns and performs actions on the selected text.
		this presentation will introduce the topics of lexical analysis in source code scanning, the limitations of this approach, and cover several tools, as well.
		in summary, lexical analysis is easy for both the developer and the authors of the tools, but has severe limitations in understanding the paths that data can take within an application, severely limiting its ability to identify potential holes.
	monkey.org /~jose/presentations/czech-rubicon02.d (207 words)

	Hyperlinked ECMA C# Language Specification
		9.3 Lexical analysis Paragraph 11 The input production defines the lexical structure of a C# source file.
		Paragraph 31 The lexical processing of a C# source file consists of reducing the file into a sequence of tokens which becomes the input to the syntactic analysis.
		Paragraph 41 When several lexical grammar productions match a sequence of characters in a source file, the lexical processing always forms the longest possible lexical element.
	www.jaggersoft.com /csharp_standard/9.3.htm (254 words)

	2. Lexical analysis
		Input to the parser is a stream of tokens, generated by the lexical analyzer.
		This chapter describes how the lexical analyzer breaks a file into tokens.
		Python uses the 7-bit ASCII character set for program text.
	www.python.org /doc/current/ref/lexical.html (241 words)

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