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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta http-equiv="Content-Type" content="text/html;charset=iso-8859-1"><title>a1: parse.cpp Source File</title><link href="doxygen.css" rel="stylesheet" type="text/css"></head><body><!-- Generated by Doxygen 1.3.9.1 --><div class="qindex"><a class="qindex" href="index.html">Main Page</a> | <a class="qindex" href="annotated.html">Class List</a> | <a class="qindex" href="files.html">File List</a> | <a class="qindex" href="functions.html">Class Members</a> | <a class="qindex" href="globals.html">File Members</a></div><h1>parse.cpp</h1><a href="parse_8cpp.html">Go to the documentation of this file.</a><div class="fragment"><pre class="fragment">00001 00008 <span class="preprocessor">#include "<a class="code" href="parse_8hpp.html">parse.hpp</a>"</span>00009 <span class="keywordtype">bool</span> inparsecar;00010 <span class="comment">// check whether chr is white space</span><a name="l00011"></a><a class="code" href="parse_8hpp.html#a1">00011</a> <span class="keywordtype">bool</span> <a class="code" href="parse_8hpp.html#a1">iswhitespace</a>(<span class="keywordtype">char</span> ch)00012 {00013 <span class="keywordflow">if</span> ((<span class="charliteral">' '</span> == ch)||(<span class="charliteral">'\n'</span> == ch)||(<span class="charliteral">'\t'</span> == ch)||(<span class="charliteral">'\r'</span> == ch)) {00014 <span class="keywordflow">return</span> <span class="keyword">true</span>;00015 } <span class="keywordflow">else</span> {00016 <span class="keywordflow">return</span> <span class="keyword">false</span>;00017 }00018 }00019 00020 <a name="l00026"></a><a class="code" href="parse_8cpp.html#a2">00026</a> <span class="keywordtype">bool</span> <a class="code" href="parse_8cpp.html#a2">is_legalnumeric</a>(string str) 00027 {00028 <span class="keywordtype">int</span> dotnum = 0;00029 <span class="keywordtype">int</span> length = str.length();00030 <span class="keywordtype">int</span> i;00031 <span class="keywordflow">if</span> (<span class="charliteral">'.'</span> == str[0]) {00032 dotnum ++;00033 } <span class="keywordflow">else</span> <span class="keywordflow">if</span> ( !((str[0] >= <span class="charliteral">'0'</span>) && (str[0] <= <span class="charliteral">'9'</span>)) && (<span class="charliteral">'+'</span>!=str[0]) && (<span class="charliteral">'-'</span>!=str[0])) {00034 <span class="keywordflow">return</span> <span class="keyword">false</span>;00035 }00036 <span class="keywordflow">for</span> (i = 1; i < length; i ++) {00037 <span class="keywordflow">if</span> (<span class="charliteral">'.'</span> == str[i]) {00038 dotnum ++;00039 } <span class="keywordflow">else</span> <span class="keywordflow">if</span> ((str[i] < <span class="charliteral">'0'</span>) || (str[i] > <span class="charliteral">'9'</span>)) {00040 <span class="keywordflow">return</span> <span class="keyword">false</span>;00041 }00042 }00043 <span class="keywordflow">if</span> (dotnum>1) {00044 <span class="keywordflow">return</span> <span class="keyword">false</span>;00045 }00046 <span class="keywordflow">return</span> <span class="keyword">true</span>;00047 }00048 <a name="l00053"></a><a class="code" href="parse_8cpp.html#a3">00053</a> <span class="keywordtype">bool</span> <a class="code" href="parse_8cpp.html#a3">is_legaloperator</a>(string str)00054 {00055 <span class="keywordflow">return</span> <span class="keyword">true</span>;00056 }00057 00058 <span class="keywordtype">void</span> <a class="code" href="main_8cpp.html#a1">readsinglesymbol</a>(string& substring, string& sexpr)00059 {00060 <span class="keywordtype">char</span> currentchar;00061 <span class="keywordtype">int</span> i = 0;00062 <span class="keywordtype">int</span> length = substring.length();00063 00064 <span class="comment">// get the first character</span>00065 currentchar = substring[i];00066 00067 <span class="keywordflow">if</span> (currentchar == <span class="charliteral">'\"'</span>) {00068 <span class="comment">// read a string literal</span>00069 sexpr += currentchar;00070 <span class="keywordflow">do</span> {00071 ++i;00072 currentchar = substring[i];00073 sexpr += currentchar;00074 } <span class="keywordflow">while</span> (currentchar != <span class="charliteral">'\"'</span> && i < length-1);00075 <span class="keywordflow">if</span> (<span class="charliteral">'\"'</span> != currentchar) {00076 cout << <span class="stringliteral">"error: illegal string"</span> << endl;00077 exit(1);00078 }00079 } <span class="keywordflow">else</span> {00080 <span class="comment">// read a numeric literal or operator</span>00081 <span class="keywordflow">do</span> {00082 sexpr += currentchar;00083 ++i;00084 <span class="keywordflow">if</span> (i >= static_cast<int>(substring.size())) {00085 <span class="keywordflow">break</span>;00086 }00087 currentchar = substring[i];00088 } <span class="keywordflow">while</span> ((!<a class="code" href="parse_8hpp.html#a1">iswhitespace</a>(currentchar)) && (currentchar != <span class="charliteral">'('</span>) && currentchar != <span class="charliteral">'\"'</span>);00089 --i;00090 }00091 substring = substring.substr(i+1, length - i - 1);00092 }00093 00094 <a name="l00099"></a><a class="code" href="parse_8cpp.html#a5">00099</a> <span class="keywordtype">void</span> <a class="code" href="parse_8cpp.html#a5">clearwhitespace</a>(string& sexpr)00100 {00101 <span class="keywordflow">if</span> (sexpr.size() <= 0) {00102 <span class="keywordflow">return</span>;00103 }00104 <span class="keywordtype">int</span> leftvalidpos;00105 <span class="keywordtype">int</span> rightvalidpos;00106 <span class="keywordtype">int</span> length = sexpr.size();00107 <span class="keywordtype">int</span> i;00108 <span class="comment">// most left non-whitespace position</span>00109 <span class="keywordflow">for</span> (i = 0; i < length; ++i) {00110 <span class="keywordflow">if</span> (<a class="code" href="parse_8hpp.html#a1">iswhitespace</a>(sexpr[i])) {00111 <span class="keywordflow">continue</span>;00112 } <span class="keywordflow">else</span> {00113 leftvalidpos = i;00114 <span class="keywordflow">break</span>;00115 }00116 }00117 00118 <span class="comment">// most right non-whitespace position</span>00119 <span class="keywordflow">for</span> (i = length - 1; i >= 0; i --) {00120 <span class="keywordflow">if</span> (<a class="code" href="parse_8hpp.html#a1">iswhitespace</a>(sexpr[i])) {00121 <span class="keywordflow">continue</span>;00122 } <span class="keywordflow">else</span> {00123 rightvalidpos = i;00124 <span class="keywordflow">break</span>;00125 }00126 }00127 00128 <span class="comment">// delete the white space at the beginning and end</span>00129 <span class="keywordflow">if</span> ( i == -1 ) sexpr = <span class="stringliteral">""</span>;00130 <span class="keywordflow">else</span> sexpr = sexpr.substr(leftvalidpos, rightvalidpos - leftvalidpos + 1);00131 }00132 <a name="l00136"></a><a class="code" href="parse_8cpp.html#a6">00136</a> <span class="keywordtype">bool</span> <a class="code" href="parse_8cpp.html#a6">is_legalexpr</a>(string sexpr)00137 {00138 <a class="code" href="parse_8cpp.html#a5">clearwhitespace</a>(sexpr);00139 <span class="keywordflow">if</span> (sexpr.length()==0) {00140 cout << <span class="stringliteral">"blank string "</span> << endl;00141 <span class="keywordflow">return</span> <span class="keyword">false</span>;00142 }00143 <span class="keywordflow">if</span> (<span class="charliteral">')'</span> == sexpr[0]) {00144 cout << <span class="stringliteral">"error: illegal s-expression"</span> << endl;00145 <span class="keywordflow">return</span> <span class="keyword">false</span>;00146 }00147 <span class="keywordflow">if</span> (<span class="charliteral">'('</span> == sexpr[0]) {00148 <span class="comment">// it is expression</span>00149 <span class="keywordtype">int</span> length = sexpr.length();00150 <span class="keywordtype">int</span> inumleftparenthesis = 1;00151 <span class="keywordtype">int</span> i;00152 <span class="keywordtype">int</span> quotationmark = 0;00153 <span class="keywordflow">for</span> (i = 1; i < length; i ++ ) {00154 <span class="keywordflow">if</span> (<span class="charliteral">'\"'</span> == sexpr[i]) {00155 quotationmark ++;00156 quotationmark = quotationmark%2;00157 } <span class="keywordflow">else</span> <span class="keywordflow">if</span> (<span class="charliteral">'('</span> == sexpr[i] && 0 == quotationmark) {00158 inumleftparenthesis ++;00159 } <span class="keywordflow">else</span> <span class="keywordflow">if</span> (<span class="charliteral">')'</span> == sexpr[i] && 0 == quotationmark) {00160 inumleftparenthesis --;00161 }00162 <span class="keywordflow">if</span> (0 == inumleftparenthesis) {00163 <span class="keywordflow">break</span>;00164 }00165 }00166 <span class="keywordflow">if</span> ((i < length - 1) || (i == length) || (inumleftparenthesis > 0) || 0 != quotationmark) {00167 cout << <span class="stringliteral">"error: illegal s-expression "</span> << endl;00168 <span class="keywordflow">return</span> <span class="keyword">false</span>;00169 }00170 } <span class="keywordflow">else</span> <span class="keywordflow">if</span> (<span class="charliteral">'\"'</span> != sexpr[0]) {00171 <span class="comment">// single element</span>00172 <span class="keywordflow">if</span> (string::npos != sexpr.find(<span class="charliteral">'('</span>) || string::npos != sexpr.find(<span class="charliteral">')'</span>) || string::npos != sexpr.find(<span class="charliteral">' '</span>) || string::npos != sexpr.find(<span class="charliteral">'\"'</span>)) {00173 cout << <span class="stringliteral">"error: illegal s-expression "</span> << endl;00174 <span class="keywordflow">return</span> <span class="keyword">false</span>;00175 }00176 <span class="comment">// check whether str is illegal numeric literal or illegal operator</span>00177 <span class="keywordflow">if</span> ((<span class="keyword">false</span> == <a class="code" href="parse_8cpp.html#a2">is_legalnumeric</a>(sexpr)) && (<span class="keyword">false</span> ==<a class="code" href="parse_8cpp.html#a3">is_legaloperator</a>(sexpr))) {00178 cout << <span class="stringliteral">"error: illegal numeric literal or illegal operator"</span> << endl;00179 <span class="keywordflow">return</span> <span class="keyword">false</span>;00180 }00181 } <span class="keywordflow">else</span> {00182 <span class="keywordtype">int</span> length = sexpr.length();00183 <span class="keywordtype">int</span> inumleft = 1;00184 <span class="keywordtype">int</span> i;00185 <span class="keywordflow">for</span> (i = 1; i < length; i ++) {00186 <span class="keywordflow">if</span> (<span class="charliteral">'\"'</span> == sexpr[i]) {00187 inumleft ++;00188 }00189 <span class="keywordflow">if</span> (2 == inumleft) {00190 <span class="keywordflow">break</span>;00191 }00192 }00193 <span class="keywordflow">if</span> ((i < length-1) || (inumleft != 2)) {00194 cout << <span class="stringliteral">"error: illegal s-expression "</span> << endl;00195 <span class="keywordflow">return</span> <span class="keyword">false</span>;00196 }⌨️ 快捷键说明
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