SCI Parser Programmer's Reference/Introduction

Official SCI Documentation

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Introduction

Author: Pablo Ghenis

Date: 21 July 1988 9:56:56 am

 

Introduction

Purpose

The parser is the part of SCI that accepts sentences from the user and allows game coders to

specify how to respond to it. For example "get the diamond" is an acceptable sentence for a

user to type, and the coder can recognize it with a "spec" such as 'get/diamond', which is

followed by SCI code to be executed IF this sentences is entered.

There are three functional blocks in the parser: the sentence parser, the spec parser and the

matcher. The sentence parser takes the words typed by the user and generates a "tree" that

describes the sentence's structure using traditional grammar rules. The spec parser accepts

"specs" and also generates tree structures. A special syntax is provided for specs since they

are more versatile than simple sentences; for example one can SPECify alternative or optional

words to be recognized. Finally, the matcher is the module that takes both trees and decides

whether or not there is a match.

The following block diagram describes the parser:

              *********           ************ 
              * User  ************* Sentence * 
              * input *      * *  * Parser   * 
              *********      * *  ************ 
                             * *       * 
              ************   * *       *    ************ 
              * External ***** *       ****** Sentence * 
              * Grammar  *     *            * Tree     *** *********** 
              ************     *            ************ * *         * 
                               *                         *** Matcher * 
              **************   *            ************ * *         * 
              * External   *****            * Spec     *** *********** 
              * Dictionary ****        ****** Tree     * 
              **************  *        *    ************ 
                              *        * 
                              *        * 
              *********       *   ************ 
              * Coder ************* Spec     * 
              * Specs *           * Parser   * 
              *********           ************

In the case of a common sentence, only a handful of comparisons may be required before a match

is found. If the user were to type in something totally inappropriate, the resulting tree

might be compared to fifty or even a hundred specs before falling through to a default answer

like "what are you trying to say?".

--3--

--- Parseable Sentences: ---

"hit the small green
tree with the ax"||'hit/tree/ax'
'hit/tree< (green<small)/ax<with'

SENTENCE	POSSIBLE MATCHING SPECS
"look"	'look[/!*]' or 'look'
"get the food"	'get/food' or 'get'
"hit the small tree"	'hit/tree<small' 'hit/tree[<small]' 'hit[/tree[<small]] 'hit'
"burn it" = "burn tree"	'burn/tree' after last sentence
"when do fairies sleep?"	'(sleep<do<fairies)<when'
"what time is it?"	'is<what<time'

 

Notes

 

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