Filter that replaces token strings with user supplied values. This is somewhat similar to <filterset> stuff.

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@271380 13f79535-47bb-0310-9956-ffa450edef68

proposal/sandbox/filterreaders/src/main/org/apache/tools/ant/filters/ReplaceTokens.java

@@ -0,0 +1,159 @@
+package org.apache.tools.ant.filters;
+
+import java.io.FilterReader;
+import java.io.IOException;
+import java.io.Reader;
+import java.util.Hashtable;
+
+import org.apache.tools.ant.types.Parameter;
+import org.apache.tools.ant.types.Parameterizable;
+
+/**
+ * Replace tokens with user supplied values
+ *
+ * Example Usage:
+ * =============
+ * <filterreader classname="org.apache.tools.ant.filters.ReplaceTokens">
+ *    <param type="tokenchar" name="begintoken" value="#"/>
+ *    <param type="tokenchar" name="endtoken" value="#"/>
+ *    <param type="token" name="DATE" value="${DATE}"/>
+ * <filterreader>
+ *
+ * @author <a href="mailto:umagesh@apache.org">Magesh Umasankar</a>
+ */
+public final class ReplaceTokens
+    extends FilterReader
+    implements Parameterizable
+{
+    private static final char DEFAULT_BEGIN_TOKEN = '@';
+
+    private static final char DEFAULT_END_TOKEN = '@';
+
+    private String storedData = null;
+
+    private Parameter[] parameters;
+
+    private Hashtable hash = new Hashtable();
+
+    private boolean initialized;
+
+    private char beginToken = DEFAULT_BEGIN_TOKEN;
+
+    private char endToken = DEFAULT_END_TOKEN;
+
+    /**
+     * Create a new filtered reader.
+     *
+     * @param in  a Reader object providing the underlying stream.
+     */
+    public ReplaceTokens(final Reader in) {
+        super(in);
+    }
+
+    /**
+     * Replace tokens with values.
+     */
+    public final int read() throws IOException {
+        if (!initialized) {
+            initialize();
+            initialized = true;
+        }
+
+        if (storedData != null && storedData.length() > 0) {
+            int ch = storedData.charAt(0);
+            if (storedData.length() > 1) {
+                storedData = storedData.substring(1);
+            } else {
+                storedData = null;
+            }
+            return ch;
+        }
+
+        int ch = in.read();
+        if (ch == beginToken) {
+            StringBuffer key = new StringBuffer("");
+            do  {
+                ch = in.read();
+                if (ch != -1) {
+                    key.append((char) ch);
+                } else {
+                    break;
+                }
+            } while (ch != endToken);
+
+            if (ch == -1) {
+                storedData = beginToken + key.toString();
+                return read();
+            } else {
+                key.setLength(key.length() - 1);
+                final String replaceWith = (String) hash.get(key.toString());
+                if (replaceWith != null) {
+                    storedData = replaceWith;
+                    return read();
+                } else {
+                    storedData = beginToken + key.toString() + endToken;
+                    return read();
+                }
+            }
+        }
+        return ch;
+    }
+
+    public final int read(final char cbuf[], final int off,
+                          final int len) throws IOException {
+        for (int i = 0; i < len; i++) {
+            final int ch = read();
+            if (ch == -1) {
+                if (i == 0) {
+                    return -1;
+                } else {
+                    return i;
+                }
+            }
+            cbuf[off + i] = (char) ch;
+        }
+        return len;
+    }
+
+    public final long skip(long n) throws IOException {
+        for (long i = 0; i < n; i++) {
+            if (in.read() == -1) {
+                return i;
+            }
+        }
+        return n;
+    }
+
+    /**
+     * Set Parameters
+     */
+    public final void setParameters(final Parameter[] parameters) {
+        this.parameters = parameters;
+        initialized = false;
+    }
+
+    /**
+     * Initialize tokens and load the replacee-replacer hashtable.
+     */
+    private final void initialize() {
+        if (parameters != null) {
+            for (int i = 0; i < parameters.length; i++) {
+                if (parameters[i] != null) {
+                    final String type = parameters[i].getType();
+                    if ("tokenchar".equals(type)) {
+                        final String name = parameters[i].getName();
+                        if ("begintoken".equals(name)) {
+                            beginToken = parameters[i].getValue().charAt(0);
+                        } else if ("endtoken".equals(name)) {
+                            endToken = parameters[i].getValue().charAt(0);
+                        }
+                    } else if ("token".equals(type)) {
+                        final String name = parameters[i].getName();
+                        final String value = parameters[i].getValue();
+                        hash.put(name, value);
+                    }
+                }
+            }
+        }
+    }
+}