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Import AnaGram (near-)release tree into Mercurial.
author David A. Holland
date Sat, 22 Dec 2007 17:52:45 -0500
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1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
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2 <TITLE>Roman Numeral Calculator</TITLE>
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3 </HEAD>
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4
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5
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6 <BODY BGCOLOR="#ffffff" BACKGROUND="tilbl6h.gif"
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7 TEXT="#000000" LINK="#0033CC"
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8 VLINK="#CC0033" ALINK="#CC0099">
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9
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10 <P>
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11 <IMG ALIGN="right" SRC="../images/agrsl6c.gif" ALT="AnaGram"
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12 WIDTH=124 HEIGHT=30 >
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13 <BR CLEAR="all">
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14 Back to <A HREF="../index.html">Index</A>
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15 <P>
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16 <IMG ALIGN="bottom" SRC="../images/rbline6j.gif" ALT="----------------------"
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17 WIDTH=1010 HEIGHT=2 >
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18 <P>
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19
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20 <H1>Roman Numeral Calculator</H1>
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21 <IMG ALIGN="bottom" SRC="../images/rbline6j.gif" ALT="----------------------"
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22 WIDTH=1010 HEIGHT=2 >
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23 <P>
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24 <H2>Introduction</H2>
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25 <P>
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26 <tt>rcalc</tt> is a simple four function desk calculator program
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27 which accepts its input and displays its output in Roman
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28 numerals. The source code for <tt>rcalc</tt> is completely contained
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29 in the file <tt>rcalc.syn</tt>.
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30
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31 <tt>rcalc</tt> illustrates the following AnaGram features:
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32 <UL>
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33 <LI> pointer input </LI>
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34 <LI> <tt>SYNTAX_ERROR</tt> macro </LI>
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35 <LI> context tracking </LI>
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36 </UL>
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37 <P>
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38
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39 <H2> Building RCALC </H2>
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40 To build a working copy of <tt>rcalc</tt>, you need to carry out the
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41 following steps:
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42 <UL>
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43 <LI> 1. Run Anagram and build a parser for <tt>rcalc</tt> </LI>
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44 <LI> 2. Using your C compiler, compile and link <tt>rcalc.c</tt>. </LI>
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45 </UL>
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46 <P>
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47
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48 <H2> Running RCALC </H2>
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49 When you run <tt>rcalc</tt> (from the command line), it will
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50 display a '<CODE>#</CODE>' prompt. Type an
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51 arithmetic expression in Roman numerals, using either upper
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52 or lower case letters. <tt>rcalc</tt> will accept addition,
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53 subtraction, multiplication and division operations, as well
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54 as unary negation, using integer arithmetic. It respects the
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55 conventional order of operations. You may use spaces and tabs
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56 freely when you type the expression and parentheses to
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57 override the natural order of computation. You may use the
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58 word <tt>NIHIL</tt> to represent zero.
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59 <P>
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60 When you have typed your expression, press Enter. <tt>rcalc</tt> will
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61 parse your expression, and if it has no syntax errors, <tt>rcalc</tt>
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62 will display the result in Roman numerals. If there is a
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63 syntax error, or if you tried to divide by zero, <tt>rcalc</tt> will
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64 display a diagnostic message, showing the location of the
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65 error. You may exit the program by pressing Enter at the
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66 prompt.
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67
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68
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69 <BR><BR><BR>
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70 <H2> Theory of Operation </H2>
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71 <tt>rcalc</tt>, like Gaul, is divided into three parts: reading
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72 input, interpreting Roman numerals, and evaluating
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73 expressions.
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74 <P>
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75 In <tt>rcalc</tt>, the main program, written in C, displays a prompt,
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76 reads a line of input, calls the parser to interpret it, and
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77 loops until it encounters end of file. The <tt>rcalc</tt> parser uses
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78 "pointer input" to parse a string already in memory. The
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79 main program needs only to set the "pointer" field in the
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80 parser control block to point to the string before calling
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81 the parser.
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82 <P>
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83 The syntax for the Roman numerals consists of
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84 straightforward enumeration of the possibilities. At every
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85 level but the thousands, there are a number of special
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86 cases, and at every level including the thousands there is
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87 the possibility of repetition. The major complicating factor
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88 is that every field, from the thousands to the units, is
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89 optional, but at least one field has to be present.
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90 <P>
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91 The expression logic is simply the conventional syntax for
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92 the basic arithmetic functions.
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93 </P>
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94
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95 <BR>
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96
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97 <IMG ALIGN="bottom" SRC="../images/rbline6j.gif" ALT="----------------------"
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98 WIDTH=1010 HEIGHT=2 >
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99 <P>
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100 <IMG ALIGN="right" SRC="../images/pslrb6d.gif" ALT="Parsifal Software"
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101 WIDTH=181 HEIGHT=25>
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102 <BR CLEAR="right">
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103 <P>
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104 Back to <A HREF="../index.html">Index</A>
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105 <P>
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106 <ADDRESS><FONT SIZE="-1"><BR><BR>
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107 AnaGram parser generator - examples<BR>
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108 Roman Numeral Calculator <BR>
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109 Copyright (c) MCMXCIII-MCMXCIX, Parsifal Software. <BR>
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110 All Rights Reserved. <BR>
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111 </FONT></ADDRESS>
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112
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113 </BODY>
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114 </HTML>
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115
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116