The Flex Lexical Analyzer - Revision history

Root: /* Exercises */

2025-05-08T16:28:36Z

Exercises

← Older revision		Revision as of 16:28, 8 May 2025
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	* [[The Flex Lexical Analyzer/Exercise 9 - Comments/code ratio in C++ and Java\|Exercise 9]] - Comments/code ratio in C++ and Java (Test 1, 2016/04/08).		* [[The Flex Lexical Analyzer/Exercise 9 - Comments/code ratio in C++ and Java\|Exercise 9]] - Comments/code ratio in C++ and Java (Test 1, 2016/04/08).
	* [[The Flex Lexical Analyzer/Exercise 10 - Message complexity\|Exercise 10]] - Message complexity.		* [[The Flex Lexical Analyzer/Exercise 10 - Message complexity\|Exercise 10]] - Message complexity.
			* [[The Flex Lexical Analyzer/Exercise 11 - PASCAL code-to-comments ratio\|Exercise 11]] - PASCAL code-to-comments ratio

	[[category:Compiladores\|Flex Lexical Analyzer]]		[[category:Compiladores\|Flex Lexical Analyzer]]
	[[category:Ensino]]		[[category:Ensino]]

Root: /* Exercises */

2022-05-20T15:26:01Z

Exercises

← Older revision		Revision as of 15:26, 20 May 2022
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	* [[The Flex Lexical Analyzer/Exercise 8 - Message list and simple accounting\|Exercise 8]] - Message list and simple accounting.		* [[The Flex Lexical Analyzer/Exercise 8 - Message list and simple accounting\|Exercise 8]] - Message list and simple accounting.
	* [[The Flex Lexical Analyzer/Exercise 9 - Comments/code ratio in C++ and Java\|Exercise 9]] - Comments/code ratio in C++ and Java (Test 1, 2016/04/08).		* [[The Flex Lexical Analyzer/Exercise 9 - Comments/code ratio in C++ and Java\|Exercise 9]] - Comments/code ratio in C++ and Java (Test 1, 2016/04/08).
			* [[The Flex Lexical Analyzer/Exercise 10 - Message complexity\|Exercise 10]] - Message complexity.
	[[category:Compiladores\|Flex Lexical Analyzer]]		[[category:Compiladores\|Flex Lexical Analyzer]]
	[[category:Ensino]]		[[category:Ensino]]

Root at 18:08, 10 February 2017

2017-02-10T18:08:28Z

← Older revision		Revision as of 18:08, 10 February 2017
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	* [http://flex.sourceforge.net/ Flex site]		* [http://flex.sourceforge.net/ Flex site]
	-->		-->

	== Examples ==		== Examples ==

Root: /* See Also */

2017-02-10T18:08:06Z

Root: /* Exercises */

2016-04-10T18:17:25Z

Exercises

← Older revision		Revision as of 18:17, 10 April 2016
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	* [[The Flex Lexical Analyzer/Exercise 7 - Text processing\|Exercise 7]] - Text processing.		* [[The Flex Lexical Analyzer/Exercise 7 - Text processing\|Exercise 7]] - Text processing.
	* [[The Flex Lexical Analyzer/Exercise 8 - Message list and simple accounting\|Exercise 8]] - Message list and simple accounting.		* [[The Flex Lexical Analyzer/Exercise 8 - Message list and simple accounting\|Exercise 8]] - Message list and simple accounting.
	* [[The Flex Lexical Analyzer/Exercise 9 - Comments/code ratio in C++ and Java\|Exercise 9]] - Comments/code ratio in C++ and Java.		* [[The Flex Lexical Analyzer/Exercise 9 - Comments/code ratio in C++ and Java\|Exercise 9]] - Comments/code ratio in C++ and Java (Test 1, 2016/04/08).
	[[category:Compiladores\|Flex Lexical Analyzer]]		[[category:Compiladores\|Flex Lexical Analyzer]]
	[[category:Ensino]]		[[category:Ensino]]

Root: /* Exercises */

2016-04-08T18:16:21Z

Exercises

← Older revision		Revision as of 18:16, 8 April 2016
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	* [[The Flex Lexical Analyzer/Exercise 7 - Text processing\|Exercise 7]] - Text processing.		* [[The Flex Lexical Analyzer/Exercise 7 - Text processing\|Exercise 7]] - Text processing.
	* [[The Flex Lexical Analyzer/Exercise 8 - Message list and simple accounting\|Exercise 8]] - Message list and simple accounting.		* [[The Flex Lexical Analyzer/Exercise 8 - Message list and simple accounting\|Exercise 8]] - Message list and simple accounting.
			* [[The Flex Lexical Analyzer/Exercise 9 - Comments/code ratio in C++ and Java\|Exercise 9]] - Comments/code ratio in C++ and Java.
	[[category:Compiladores\|Flex Lexical Analyzer]]		[[category:Compiladores\|Flex Lexical Analyzer]]
	[[category:Ensino]]		[[category:Ensino]]

Root at 14:51, 6 April 2015

2015-04-06T14:51:16Z

← Older revision		Revision as of 14:51, 6 April 2015
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	* [[The Flex Lexical Analyzer/Exercise 8 - Message list and simple accounting\|Exercise 8]] - Message list and simple accounting.		* [[The Flex Lexical Analyzer/Exercise 8 - Message list and simple accounting\|Exercise 8]] - Message list and simple accounting.

	[[category:Compiladores]]		[[category:Compiladores\|Flex Lexical Analyzer]]
	[[category:Ensino]]		[[category:Ensino]]

Root at 14:33, 6 April 2015

2015-04-06T14:33:48Z

← Older revision		Revision as of 14:33, 6 April 2015
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	* [[The Flex Lexical Analyzer/Exercise 8 - Message list and simple accounting\|Exercise 8]] - Message list and simple accounting.		* [[The Flex Lexical Analyzer/Exercise 8 - Message list and simple accounting\|Exercise 8]] - Message list and simple accounting.

	[[category:~~Compilers~~]]		[[category:Compiladores]]
	[[category:~~Teaching~~]]		[[category:Ensino]]

Root: /* How to Debug a Flex Specification */

2015-02-13T19:59:54Z

How to Debug a Flex Specification

← Older revision		Revision as of 19:59, 13 February 2015
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	== How to Debug a Flex Specification ==		== How to Debug a Flex Specification ==

	There are various flags and variables to activate the debug functionality in Flex (there is no fundamental need to insert code such as printfs or similar, even through, of course, that style of debugging is also possible).		There are various flags and variables to activate the debug functionality in Flex, i.e., there is no fundamental need to insert code such as printfs or similar, even through, of course, that style of debugging is also possible. These other ways are often much superior to printfs, since they can easily inform the programmer about matched rules, triggered actions, and so on.

	In the Flex specification file:		Generation of debug code is requested by activating the corresponding option. In the Flex specification file, insert:
	%option debug		%option debug

	This flag suffices when developing in C. When using C++ scanners ('''%option c++'''), even though the above flag still generates debug code, it's still necessary to tell the scanner to actually output debug information. This can be done by calling the '''set_debug''' method with a non-zero argument (this can be done ~~conveniently~~ at the start of the rules section in a Flex specification file -- note how the action is indented from the left and without any rule):		This flag suffices to produce output information when developing in C. When using C++ scanners ('''%option c++'''), even though the above flag still generates debug code, it's still necessary to tell the scanner to actually output debug information. This can be done by calling the '''set_debug''' method with a non-zero argument (this can be conveniently done at the start of the rules section in a Flex specification file -- note how the action is indented from the left and without any rule):

	%%		%option debug
	{ set_debug(1); }		...

			%%
			{ set_debug(1); }

			... other rules...

			%%

	~~Also, the~~ YYDEBUG environment variable will activate the debug messages '''both''' in Flex and YACC (allowing simultaneous debugging of token recognition by the scanner and corresponding use by the parser). In the command line (syntax may vary, depending on the actual environment definition circumstances):		The YYDEBUG environment variable will activate the debug messages '''both''' in Flex and YACC (allowing simultaneous debugging of token recognition by the scanner and corresponding use by the parser).

			In the shell's command line (syntax may vary, depending on the actual environment definition circumstances):
	export YYDEBUG=1		export YYDEBUG=1

Root: /* Exercises */

2012-05-07T17:42:23Z

Exercises

← Older revision		Revision as of 17:42, 7 May 2012
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	* [[The Flex Lexical Analyzer/Exercise 6 - Playlist processing\|Exercise 6]] - Playlist processing.		* [[The Flex Lexical Analyzer/Exercise 6 - Playlist processing\|Exercise 6]] - Playlist processing.
	* [[The Flex Lexical Analyzer/Exercise 7 - Text processing\|Exercise 7]] - Text processing.		* [[The Flex Lexical Analyzer/Exercise 7 - Text processing\|Exercise 7]] - Text processing.
			* [[The Flex Lexical Analyzer/Exercise 8 - Message list and simple accounting\|Exercise 8]] - Message list and simple accounting.

	[[category:Compilers]]		[[category:Compilers]]
	[[category:Teaching]]		[[category:Teaching]]

← Older revision		Revision as of 16:28, 8 May 2025
Line 73:		Line 73:
	* [[The Flex Lexical Analyzer/Exercise 9 - Comments/code ratio in C++ and Java\|Exercise 9]] - Comments/code ratio in C++ and Java (Test 1, 2016/04/08).		* [[The Flex Lexical Analyzer/Exercise 9 - Comments/code ratio in C++ and Java\|Exercise 9]] - Comments/code ratio in C++ and Java (Test 1, 2016/04/08).
	* [[The Flex Lexical Analyzer/Exercise 10 - Message complexity\|Exercise 10]] - Message complexity.		* [[The Flex Lexical Analyzer/Exercise 10 - Message complexity\|Exercise 10]] - Message complexity.
			* [[The Flex Lexical Analyzer/Exercise 11 - PASCAL code-to-comments ratio\|Exercise 11]] - PASCAL code-to-comments ratio

	[[category:Compiladores\|Flex Lexical Analyzer]]		[[category:Compiladores\|Flex Lexical Analyzer]]
	[[category:Ensino]]		[[category:Ensino]]

← Older revision		Revision as of 15:26, 20 May 2022
Line 72:		Line 72:
	* [[The Flex Lexical Analyzer/Exercise 8 - Message list and simple accounting\|Exercise 8]] - Message list and simple accounting.		* [[The Flex Lexical Analyzer/Exercise 8 - Message list and simple accounting\|Exercise 8]] - Message list and simple accounting.
	* [[The Flex Lexical Analyzer/Exercise 9 - Comments/code ratio in C++ and Java\|Exercise 9]] - Comments/code ratio in C++ and Java (Test 1, 2016/04/08).		* [[The Flex Lexical Analyzer/Exercise 9 - Comments/code ratio in C++ and Java\|Exercise 9]] - Comments/code ratio in C++ and Java (Test 1, 2016/04/08).
			* [[The Flex Lexical Analyzer/Exercise 10 - Message complexity\|Exercise 10]] - Message complexity.
	[[category:Compiladores\|Flex Lexical Analyzer]]		[[category:Compiladores\|Flex Lexical Analyzer]]
	[[category:Ensino]]		[[category:Ensino]]

← Older revision		Revision as of 18:17, 10 April 2016
Line 71:		Line 71:
	* [[The Flex Lexical Analyzer/Exercise 7 - Text processing\|Exercise 7]] - Text processing.		* [[The Flex Lexical Analyzer/Exercise 7 - Text processing\|Exercise 7]] - Text processing.
	* [[The Flex Lexical Analyzer/Exercise 8 - Message list and simple accounting\|Exercise 8]] - Message list and simple accounting.		* [[The Flex Lexical Analyzer/Exercise 8 - Message list and simple accounting\|Exercise 8]] - Message list and simple accounting.
	* [[The Flex Lexical Analyzer/Exercise 9 - Comments/code ratio in C++ and Java\|Exercise 9]] - Comments/code ratio in C++ and Java.		* [[The Flex Lexical Analyzer/Exercise 9 - Comments/code ratio in C++ and Java\|Exercise 9]] - Comments/code ratio in C++ and Java (Test 1, 2016/04/08).
	[[category:Compiladores\|Flex Lexical Analyzer]]		[[category:Compiladores\|Flex Lexical Analyzer]]
	[[category:Ensino]]		[[category:Ensino]]

← Older revision		Revision as of 18:16, 8 April 2016
Line 71:		Line 71:
	* [[The Flex Lexical Analyzer/Exercise 7 - Text processing\|Exercise 7]] - Text processing.		* [[The Flex Lexical Analyzer/Exercise 7 - Text processing\|Exercise 7]] - Text processing.
	* [[The Flex Lexical Analyzer/Exercise 8 - Message list and simple accounting\|Exercise 8]] - Message list and simple accounting.		* [[The Flex Lexical Analyzer/Exercise 8 - Message list and simple accounting\|Exercise 8]] - Message list and simple accounting.
			* [[The Flex Lexical Analyzer/Exercise 9 - Comments/code ratio in C++ and Java\|Exercise 9]] - Comments/code ratio in C++ and Java.
	[[category:Compiladores\|Flex Lexical Analyzer]]		[[category:Compiladores\|Flex Lexical Analyzer]]
	[[category:Ensino]]		[[category:Ensino]]

← Older revision		Revision as of 18:08, 10 February 2017
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	export YYDEBUG=1		export YYDEBUG=1

	== See Also ==		<!--== See Also ==

	* [http://flex.sourceforge.net/manual/ Flex manual @ sourceforge]		* [http://flex.sourceforge.net/manual/ Flex manual @ sourceforge]
	* [http://flex.sourceforge.net/ Flex site]		* [http://flex.sourceforge.net/ Flex site]
			-->

	== Examples ==		== Examples ==