Mercurial > ~dholland > hg > ag > index.cgi
diff doc/misc/html/gtrace.html @ 0:13d2b8934445
Import AnaGram (near-)release tree into Mercurial.
| author | David A. Holland |
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| date | Sat, 22 Dec 2007 17:52:45 -0500 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/doc/misc/html/gtrace.html Sat Dec 22 17:52:45 2007 -0500 @@ -0,0 +1,155 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN"> +<HTML> +<HEAD> +<TITLE>AnaGram's Grammar Trace Facility</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="RIGHT"> +</P> + +<P> +Back to <A HREF="index.html">Index</A> +<IMG ALIGN="bottom" SRC="images/rbline6j.gif" ALT="----------------------" + WIDTH=1010 HEIGHT=2 > + +<H2>AnaGram's Grammar Trace</H2> +<IMG ALIGN="bottom" SRC="images/rbline6j.gif" ALT="----------------------" + WIDTH=1010 HEIGHT=2 > + +<P> + +The Grammar Trace facility lets you examine the workings of your +parser in detail, <ITALIC>interactively</ITALIC>. You can use Grammar Trace even +<ITALIC>before</ITALIC> you +write any code to attach to the rules of your grammar, and before actually +building a parser. If you have a test file available, you may prefer to use <A +HREF="ftrace.html"><STRONG>File Trace</STRONG></A>. +<P> +Using the various options associated with this trace +you can set up a representation of the parser state stack and parser +state as they might appear in the course of execution of your +parser. You can then examine the allowable input tokens and the +changes to the state and the state stack caused by any input tokens you +choose. + +<IMG ALIGN="right" SRC="gramtr6g.gif" ALT="sample Grammar Trace window" + WIDTH=489 HEIGHT=338 VSPACE=8 HSPACE=8 > + + +<P> +AnaGram now provides a combo box where you can enter input characters +for a Grammar Trace, in addition to choosing tokens. This means you can +run a Grammar Trace like a <A +HREF="ftrace.html">File Trace</A> where the test file is replaced +by the combo box characters you type. This is a very convenient way +to check out your grammar. +</P> + +<BR> + +<H3> Starting Grammar Traces:</H3> + +A Grammar Trace can be selected from either the Action Menu or the +Control Panel toolbar once your grammar has been analyzed. There are +also prebuilt grammar traces like the Conflict Trace and the +Auxiliary Trace, which can be selected from the Auxiliary Windows +popup menu for certain AnaGram windows or panes. +<P> +Like File Trace, a Grammar Trace presents three principal panes. These +are a Parser Stack pane on the left, an Allowable Input pane on the +right, and a Rule Stack pane at the bottom. +<P> +Initially, the Parser Stack will consist of a single line, which +represents the initial configuration of your parser. The first column +will show zero, which is the value of the parser stack +index. The second column will show the state number of the parser, +initially S000. The third column of the Parser Stack, which shows the +token seen at that state, is initially blank. The Rule Stack will +likewise be at level 0, state 000. The active pane of the Grammar +Trace will be the Allowable Input pane, ready for you to choose a +token. +<BR> + +<H3> Using Grammar Trace </H3> + +At any stage, the Parser Stack pane represents a parse +in progress. It shows the sequence of tokens that have +been input so far and the states in which they were +seen. When a production is complete and the grammar rule +is reduced, the tokens that make up the rule are removed +from the stack and replaced by the token on the left +side of the production. The Rule Stack pane shows you all +the grammar rules that are currently active +at any level in the stack. +<P> + +To explore your grammar, choose a token from the Allowable Input +pane. This pane shows the tokens allowable at the current state of the +grammar, and the actions that result when the tokens are chosen. +The Action field for each token shows whether it +would cause a shift or a reduction, and the new state or the rule +reduced. It is blank if the parser action is a compound action. + +<P> +Select a token by double-clicking it with the left mouse button or by +positioning the cursor bar on the token and pressing Enter. +Then the Parser Stack and Rule +Stack will be modified to reflect the input choice you made. Note +that the panes in the Grammar Trace window are synched with each +other and also with your syntax file window if it is on-screen. The +Rule Stack is particularly useful for seeing the relationship between +the Parser Stack contents and your grammar. + +<P> +You may now continue stepping through your grammar. At any time, as an +alternative to choosing tokens in the Allowable Input pane, you may +type text in the combo box at the bottom of the Grammar Trace +window and either press Enter or select the Proceed button to parse +the text. The Single Step button will accept the combo box input one +step at a time if the combo box is active, or the highlighted token +if Allowable Input is active. + +<P> You can back up the parse by +moving the cursor bar in the Parser Stack window to the desired level +and double-clicking the highlighted token in Allowable Input. You can +reset the trace to the beginning with the Reset button. + +<P> +If you are using semantically determined productions, a Reduction +Choices pane will appear to the left of the Rule Stack when it is +time to reduce such a production. Select the desired reduction token +from the pane before continuing with the parse. + +<P> +All Grammar Trace activity updates the trace coverage counts. +<P> + +<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> + Grammar Trace<BR> + Copyright © 1993-1999, Parsifal Software. <BR> + All Rights Reserved.<BR> +</FONT></ADDRESS> + +</BODY> +</HTML> + +