Mercurial > ~dholland > hg > ag > index.cgi
diff doc/misc/html/summary.html @ 0:13d2b8934445
Import AnaGram (near-)release tree into Mercurial.
| author | David A. Holland |
|---|---|
| date | Sat, 22 Dec 2007 17:52:45 -0500 |
| parents | |
| children |
line wrap: on
line diff
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/doc/misc/html/summary.html Sat Dec 22 17:52:45 2007 -0500 @@ -0,0 +1,203 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN"> +<HTML> +<HEAD> +<TITLE>Summary of AnaGram Notation</TITLE> +</HEAD> + +<BODY BGCOLOR="#ffffff" BACKGROUND="tilbl6h.gif" + TEXT="#000000" LINK="#0033CC" + VLINK="#CC0033" ALINK="#CC0099"> + +<P> + +<IMG ALIGN="right" SRC="images/agrsl6c.gif" ALT="AnaGram" + WIDTH=124 HEIGHT=30> +<BR CLEAR="all"> +Back to <A HREF="index.html">Index</A> +<P> +<IMG ALIGN="bottom" SRC="images/rbline6j.gif" ALT="----------------------" + WIDTH=1010 HEIGHT=2 > + +<BR CLEAR="all"> + + +<H1 ALIGN="LEFT">Summary of AnaGram Notation</H1> +<IMG ALIGN="bottom" SRC="images/rbline6j.gif" ALT="----------------------" + WIDTH=1010 HEIGHT=2 > +</P> +<BR> + +The rules for using AnaGram are given in Chapters 8 and 9 of +the AnaGram User's Guide. This page contains a brief summary. +Section headings and terms which appear in <b> bold face</b> can be found +in the online <b> Help Topics</b>. +<P> +<BR> + +<H2>Lexical Conventions</H2> +AnaGram allows the free use of spaces, tabs and <b> comments</b>. +Both C style and C++ style comments are allowed. Blank lines are +allowed, but only <i>between</i> statements. +<p> +AnaGram statements may continue onto following lines as long +as they are clearly incomplete. Normally this rule is satisfied by +dangling punctuation or open parentheses, brackets, or braces. In no +case can a statement continue over a blank line. +<P> +<BR> + +<H2>Names</H2> +Symbol names must begin with a letter or underscore, and may +contain letters, digits, or underscores. They may also contain embedded spaces, tabs, and comments. Any sequence of embedded +space, however, is replaced by a single blank character. +<p> +The names <b> eof</b>, <b> error</b>, and <b> grammar</b> have special meanings. +<P> +<BR> + +<H2>Character Representations</H2> +You may represent a character using the same rules as for +<b> character constants</b> in C. You may also use signed integers, using +either decimal, octal or hexadecimal formats, again following the +rules for C. You may specify control characters using ^, e.g., ^C. +<P> +<BR> + +<H2>Character Ranges</H2> +Character ranges may be specified either in the form 'a-z' or +with two simple characters separated by "..", e.g, 32..255. +<P> +<BR> + +<H2>Character Sets</H2> +Use the following operators for more complex character sets: +<DL> + <DT>Set <b> union</b></DT><DD>A + B</DD> + <DT>Set <b> difference</b></DT><DD>A - B</DD> + <DT>Set <b> intersection</b></DT><DD>A & B</DD> + <DT>Set <b> complement</b></DT><DD>~A</DD> +</DL> + +AnaGram interprets a single character to mean the set containing +only the character itself. +<P> +<BR> + +<H2>Keywords</H2> +A character string enclosed in double quotes is a <B>keyword</B>. The +rules for writing keyword strings are the same as for literal strings +in C. AnaGram parsers have special lookahead logic to recognize +keywords, so that keywords get special treatment. They are <i>not</i> +equivalent to the corresponding sequence of single characters. +<P> +<BR> + +<H2>Tokens</H2> The units of a grammar are called <A +HREF="gloss.html#Token">tokens</A>. <A HREF="gloss.html#Terminal"> +Terminal tokens </A>may be <b> character sets</b>, <b> keywords</b>, +<b> immediate actions</b>, or <b> virtual productions</b>. <A +HREF="gloss.html#Nonterminal"> Nonterminal tokens</A> are defined +in terms of other tokens by means of productions. <P> <BR> + +<H2>Productions</H2> +A <A HREF="gloss.html#Production">production</A> consists of one or more +token names on the left, an arrow ( <CODE>-></CODE> ), and a +<A HREF="gloss.html#GrammarRule"> +grammar rule</A> on the right. A production with more than one name on +the left is called a <A HREF="gloss.html#SemanticallyDetermined"> +semantically determined production</A>. Additional productions with +the same left side may be joined by using | or another arrow. The +arrow, if used, must start a new line. + +<P> If the token on the left +side of a production is called <i>grammar</i> or is tagged with a +following dollar sign, it is taken to be the <A +HREF="gloss.html#GrammarToken"> grammar token</A>, or goal token for +the grammar. + +<P> The names on the left side of a +production may be preceded by a type cast indicating the data type of +the <A HREF="gloss.html#SemanticValue"> semantic value</A> of the +named tokens. + +<P> A grammar rule is a sequence of <A HREF="gloss.html#RuleElement"> +rule elements</A> joined by commas. The rule elements may be <b> +character sets</b>, <b> keywords</b>, <b> token names</b>, <b> virtual +productions</b>, or <b> immediate actions</b>. + +<P> A <A HREF="gloss.html#VirtualProduction">virtual +production</A> is a token name or character set expression followed by +? or ?..., or a sequence of one or more rules, joined by vertical bars +( | ) , inside brackets or braces and optionally followed by an +ellipsis (...). The ? indicates an optional token. Braces indicate a +choice among the listed rules. Brackets indicate an optional choice. +The ellipsis represents unlimited repetition. <P> <BR> + +<H2>Reduction Procedures</H2> +A <A HREF="gloss.html#ReductionProcedure">reduction procedure</A> is a +piece of C or C++ code following a grammar rule that is to be executed +when the rule is recognized in the parser's input stream. Reduction +procedures may be short form: a single expression followed by a +semicolon, or long form: a block of code enclosed in braces. In either +case they are preceded by an equal sign. Short form procedures may not +continue onto another line. + +<P> Reduction procedures may access the +<A HREF="gloss.html#SemanticValue"> semantic values</A> of tokens in +the grammar rule to which they are attached. To each token whose value +is needed append a colon and the variable name used for the token value +in the reduction procedure. In a short form reduction procedure, the +value of the expression is assigned to the <A +HREF="gloss.html#ReductionToken"> reduction token</A>, the token on +the left side of the production. In a long form procedure, use the +return statement to assign a value to the token on the left side of the +production. <p> An <b> immediate action</b> differs from a reduction +procedure in that it may occur in the middle of a grammar rule. To +distinguish it from a reduction procedure, it begins with an +exclamation point rather than an equal sign. <P> <BR> + +<H2>Definitions</H2> +You may assign names to frequently used character sets, virtual +productions, keywords, or immediate actions by using a definition +statement consisting of a name, an equal sign and the entity to be +named. +<P> +<BR> + +<H2>Configuration Section</H2> +A configuration section is a block of special statements enclosed +in brackets. These are either <b> attribute statements</b> or assign values +to <b> configuration parameters</b> or switches, all of which are +described in on-line help windows. +<P> +<BR> + +<H2>Embedded C</H2> +You may include C or C++ code to support your reduction +procedures at any point in your grammar by enclosing it in braces. +The beginning brace must be on a fresh line, and no other statement +may follow on the same line as the terminating brace. A +block of embedded C at the very beginning of a <b> syntax file</b> is +called the <b> C prologue</b>. + +<P> +<BR> + +<IMG ALIGN="bottom" SRC="images/rbline6j.gif" ALT="----------------------" + WIDTH=1010 HEIGHT=2 > +<P> +<IMG ALIGN="right" SRC="images/pslrb6d.gif" ALT="Parsifal Software" + WIDTH=181 HEIGHT=25> +<BR CLEAR="right"> +<P> +Back to <A HREF="index.html">Index</A> +<P> +<ADDRESS><FONT SIZE="-1"> + AnaGram parser generator - documentation<BR> + Summary of AnaGram Notation<BR> + Copyright © 1993-1999, Parsifal Software. <BR> + All Rights Reserved.<BR> +</FONT></ADDRESS> + +</BODY> +</HTML>