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12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14  * version 2 for more details (a copy is included in the LICENSE file that
15  * accompanied this code).
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17  * You should have received a copy of the GNU General Public License version
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25 
26 package build.tools.spp;
27 
28 import java.util.*;
29 import java.util.regex.*;
30 
31 /*
32  * Spp: A simple regex-based stream preprocessor based on Mark Reinhold's
33  *      sed-based spp.sh
34  *
35  * Usage: java build.tools.spp.Spp [-be] [-nel] [-Kkey] -Dvar=value ... <in >out
36  *
37  * If -nel is declared then empty lines will not be substituted for lines of
38  * text in the template that do not appear in the output.
39  *
40  *   Meaningful only at beginning of line, works with any number of keys:
41  *
42  *    #if[key]              Includes text between #if/#end if -Kkey specified,
43  *    #else[key]            otherwise changes text to blank lines; key test
44  *    #end[key]             may be negated by prefixing !, e.g., #if[!key]
45  *
46  *    #begin                If -be is specified then lines up to and including
47  *    #end                  #begin, and from #end to EOF, are deleted
48  *
49  *    #warn                 Changed into warning that file is generated
50  *
51  *    // ##                 Changed into blank line
52  *
53  *  Meaningful anywhere in line
54  *
55  *    {#if[key]?yes}        Expands to yes if -Kkey specified
56  *    {#if[key]?yes:no}     Expands to yes if -Kkey, otherwise no
57  *    {#if[!key]?yes}       Expands to yes if -Kother
58  *    {#if[!key]?yes:no}    Expands to yes if -Kother, otherwise no
59  *    $var$                 Expands to value if -Dvar=value given
60  *
61  *    yes, no must not contain whitespace
62  *
63  * @author Xueming Shen
64  */
65 
66 public class Spp {
main(String args[])67     public static void main(String args[]) throws Exception {
68         Map<String, String> vars = new HashMap<>();
69         Set<String> keys = new HashSet<>();
70         boolean be = false;
71         boolean el = true;
72 
73         for (String arg:args) {
74             if (arg.startsWith("-D")) {
75                 int i = arg.indexOf('=');
76                 vars.put(arg.substring(2, i),arg.substring(i+1));
77             } else if (arg.startsWith("-K")) {
78                 keys.add(arg.substring(2));
79             } else if ("-be".equals(arg)) {
80                 be = true;
81             } else if ("-nel".equals(arg)) {
82                 el = false;
83             } else {
84                 System.err.println("Usage: java build.tools.spp.Spp [-be] [-nel] [-Kkey] -Dvar=value ... <in >out");
85                 System.exit(-1);
86             }
87         }
88 
89         StringBuffer out = new StringBuffer();
90         new Spp().spp(new Scanner(System.in),
91                       out, "",
92                       keys, vars, be, el,
93                       false);
94         System.out.print(out.toString());
95     }
96 
97     static final String LNSEP = System.getProperty("line.separator");
98     static final String KEY = "([a-zA-Z0-9]+)";
99     static final String VAR = "([a-zA-Z0-9_\\-]+)";
100     static final String TEXT = "([a-zA-Z0-9&;,.<>/#() \\?\\[\\]\\$]+)"; // $ -- hack embedded $var$
101 
102     static final int GN_NOT = 1;
103     static final int GN_KEY = 2;
104     static final int GN_YES = 3;
105     static final int GN_NO  = 5;
106     static final int GN_VAR = 6;
107 
108     final Matcher   ifkey = Pattern.compile("^#if\\[(!)?" + KEY + "\\]").matcher("");
109     final Matcher elsekey = Pattern.compile("^#else\\[(!)?" + KEY + "\\]").matcher("");
110     final Matcher  endkey = Pattern.compile("^#end\\[(!)?" + KEY + "\\]").matcher("");
111     final Matcher  vardef = Pattern.compile("\\{#if\\[(!)?" + KEY + "\\]\\?" + TEXT + "(:"+ TEXT + ")?\\}|\\$" + VAR + "\\$").matcher("");
112     final Matcher vardef2 = Pattern.compile("\\$" + VAR + "\\$").matcher("");
113 
append(StringBuffer buf, String ln, Set<String> keys, Map<String, String> vars)114     void append(StringBuffer buf, String ln,
115                 Set<String> keys, Map<String, String> vars) {
116         vardef.reset(ln);
117         while (vardef.find()) {
118             String repl = "";
119             if (vardef.group(GN_VAR) != null)
120                 repl = vars.get(vardef.group(GN_VAR));
121             else {
122                 boolean test = keys.contains(vardef.group(GN_KEY));
123                 if (vardef.group(GN_NOT) != null)
124                     test = !test;
125                 repl = test?vardef.group(GN_YES):vardef.group(GN_NO);
126                 if (repl == null)
127                     repl = "";
128                 else {  // embedded $var$
129                     while (vardef2.reset(repl).find()) {
130                         repl = vardef2.replaceFirst(vars.get(vardef2.group(1)));
131                     }
132                 }
133             }
134             vardef.appendReplacement(buf, repl);
135         }
136         vardef.appendTail(buf);
137     }
138 
139     // return true if #end[key], #end or EOF reached
spp(Scanner in, StringBuffer buf, String key, Set<String> keys, Map<String, String> vars, boolean be, boolean el, boolean skip)140     boolean spp(Scanner in, StringBuffer buf, String key,
141                 Set<String> keys, Map<String, String> vars,
142                 boolean be, boolean el, boolean skip) {
143         while (in.hasNextLine()) {
144             String ln = in.nextLine();
145             if (be) {
146                 if (ln.startsWith("#begin")) {
147                     buf.setLength(0);      //clean up to this line
148                     continue;
149                 }
150                 if (ln.equals("#end")) {
151                     while (in.hasNextLine())
152                         in.nextLine();
153                     return true;           //discard the rest to EOF
154                 }
155             }
156             if (ifkey.reset(ln).find()) {
157                 String k = ifkey.group(GN_KEY);
158                 boolean test = keys.contains(k);
159                 if (ifkey.group(GN_NOT) != null)
160                     test = !test;
161                 if (el) buf.append(LNSEP);
162                 if (!spp(in, buf, k, keys, vars, be, el, skip || !test)) {
163                     spp(in, buf, k, keys, vars, be, el, skip || test);
164                 }
165                 continue;
166             }
167             if (elsekey.reset(ln).find()) {
168                 if (!key.equals(elsekey.group(GN_KEY))) {
169                     throw new Error("Mis-matched #if-else-end at line <" + ln + ">");
170                 }
171                 if (el) buf.append(LNSEP);
172                 return false;
173             }
174             if (endkey.reset(ln).find()) {
175                 if (!key.equals(endkey.group(GN_KEY))) {
176                     throw new Error("Mis-matched #if-else-end at line <" + ln + ">");
177                 }
178                 if (el) buf.append(LNSEP);
179                 return true;
180             }
181             if (ln.startsWith("#warn")) {
182                 ln = "// -- This file was mechanically generated: Do not edit! -- //";
183             } else if (ln.trim().startsWith("// ##")) {
184                 ln = "";
185             }
186             if (!skip) {
187                 append(buf, ln, keys, vars);
188                 if (!el) buf.append(LNSEP);
189             }
190             if (el) buf.append(LNSEP);
191         }
192         return true;
193     }
194 }
195