1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34 package groovy.text;
35
36 import groovy.lang.Binding;
37 import groovy.lang.GroovyShell;
38 import groovy.lang.Script;
39 import groovy.lang.Writable;
40
41 import java.io.BufferedReader;
42 import java.io.IOException;
43 import java.io.PrintWriter;
44 import java.io.Reader;
45 import java.io.StringWriter;
46 import java.io.Writer;
47 import java.util.Map;
48
49 import org.codehaus.groovy.control.CompilationFailedException;
50 import org.codehaus.groovy.runtime.InvokerHelper;
51
52 /***
53 * This simple template engine uses JSP <% %> script and <%= %> expression syntax. It also lets you use normal groovy expressions in
54 * the template text much like the new JSP EL functionality. The variable 'out' is bound to the writer that the template is being written to.
55 *
56 * @author sam
57 * @author Christian Stein
58 */
59 public class SimpleTemplateEngine extends TemplateEngine {
60
61 private final boolean verbose;
62
63 public SimpleTemplateEngine() {
64 this(false);
65 }
66
67 public SimpleTemplateEngine(boolean verbose) {
68 this.verbose = verbose;
69 }
70
71 public Template createTemplate(Reader reader) throws CompilationFailedException, IOException {
72 SimpleTemplate template = new SimpleTemplate();
73 GroovyShell shell = new GroovyShell();
74 String script = template.parse(reader);
75 if (verbose) {
76 System.out.println("\n-- script source --");
77 System.out.print(script);
78 System.out.println("\n-- script end --\n");
79 }
80 template.script = shell.parse(script);
81 return template;
82 }
83
84 private static class SimpleTemplate implements Template {
85
86 protected Script script;
87
88 public Writable make() {
89 return make(null);
90 }
91
92 public Writable make(final Map map) {
93 return new Writable() {
94 /***
95 * Write the template document with the set binding applied to the writer.
96 *
97 * @see groovy.lang.Writable#writeTo(java.io.Writer)
98 */
99 public Writer writeTo(Writer writer) {
100 Binding binding;
101 if (map == null)
102 binding = new Binding();
103 else
104 binding = new Binding(map);
105 Script scriptObject = InvokerHelper.createScript(script.getClass(), binding);
106 PrintWriter pw = new PrintWriter(writer);
107 scriptObject.setProperty("out", pw);
108 scriptObject.run();
109 pw.flush();
110 return writer;
111 }
112
113 /***
114 * Convert the template and binding into a result String.
115 *
116 * @see java.lang.Object#toString()
117 */
118 public String toString() {
119 try {
120 StringWriter sw = new StringWriter();
121 writeTo(sw);
122 return sw.toString();
123 } catch (Exception e) {
124 return e.toString();
125 }
126 }
127 };
128 }
129
130 /***
131 * Parse the text document looking for <% or <%= and then call out to the appropriate handler, otherwise copy the text directly
132 * into the script while escaping quotes.
133 *
134 * @param reader
135 * @return
136 * @throws IOException
137 */
138 protected String parse(Reader reader) throws IOException {
139 if (!reader.markSupported()) {
140 reader = new BufferedReader(reader);
141 }
142 StringWriter sw = new StringWriter();
143 startScript(sw);
144 boolean start = false;
145 int c;
146 while ((c = reader.read()) != -1) {
147 if (c == '<') {
148 reader.mark(1);
149 c = reader.read();
150 if (c != '%') {
151 sw.write('<');
152 reader.reset();
153 } else {
154 reader.mark(1);
155 c = reader.read();
156 if (c == '=') {
157 groovyExpression(reader, sw);
158 } else {
159 reader.reset();
160 groovySection(reader, sw);
161 }
162 }
163 continue;
164 }
165 if (c == '\"') {
166 sw.write('//');
167 }
168
169
170
171 if (c == '\n' || c == '\r') {
172 if (c == '\r') {
173 reader.mark(1);
174 c = reader.read();
175 if (c != '\n') {
176 reader.reset();
177 }
178 }
179 sw.write("//n\");\nout.print(\"");
180 continue;
181 }
182 sw.write(c);
183 }
184 endScript(sw);
185 String result = sw.toString();
186 return result;
187 }
188
189 private void startScript(StringWriter sw) {
190 sw.write("/* Generated by SimpleTemplateEngine */\n");
191 sw.write("out.print(\"");
192 }
193
194 private void endScript(StringWriter sw) {
195 sw.write("\");\n");
196 }
197
198 /***
199 * Closes the currently open write and writes out the following text as a GString expression until it reaches an end %>.
200 *
201 * @param reader
202 * @param sw
203 * @throws IOException
204 */
205 private void groovyExpression(Reader reader, StringWriter sw) throws IOException {
206 sw.write("\");out.print(\"${");
207 int c;
208 while ((c = reader.read()) != -1) {
209 if (c == '%') {
210 c = reader.read();
211 if (c != '>') {
212 sw.write('%');
213 } else {
214 break;
215 }
216 }
217 if (c != '\n' && c != '\r') {
218 sw.write(c);
219 }
220 }
221 sw.write("}\");\nout.print(\"");
222 }
223
224 /***
225 * Closes the currently open write and writes the following text as normal Groovy script code until it reaches an end %>.
226 *
227 * @param reader
228 * @param sw
229 * @throws IOException
230 */
231 private void groovySection(Reader reader, StringWriter sw) throws IOException {
232 sw.write("\");");
233 int c;
234 while ((c = reader.read()) != -1) {
235 if (c == '%') {
236 c = reader.read();
237 if (c != '>') {
238 sw.write('%');
239 } else {
240 break;
241 }
242 }
243
244
245
246
247 sw.write(c);
248
249 }
250 sw.write(";\nout.print(\"");
251 }
252
253 }
254 }