Basic implementation and some tests.

src/main/java/com/samskivert/mustache/Mustache.java

@@ -3,15 +3,23 @@
 
 package com.samskivert.mustache;
 
+import java.io.IOException;
 import java.io.Reader;
 import java.io.StringReader;
 import java.io.Writer;
 import java.lang.reflect.Array;
+import java.util.ArrayList;
 import java.util.Iterator;
+import java.util.List;
 import java.util.Map;
 
 /**
  * Provides <a href="http://mustache.github.com/">Mustache</a> templating services.
+ * <p> Limitations:
+ * <ul><li> Only one or two character delimiters are supported when using {{=ab cd=}} to change
+ * delimiters.
+ * <li> {{< include}} is not supported. We specifically do not want the complexity of handling the
+ * automatic loading of dependent templates. </ul>
  */
 public class Mustache
 {
@@ -26,50 +34,273 @@ public class Mustache
     /**
      * Compiles the supplied template into a repeatedly executable intermediate form.
      */
-    public static Template compile (Reader template)
+    public static Template compile (Reader source)
     {
-        return null; // TODO
+        // a hand-rolled parser; whee!
+        Accumulator accum = new Accumulator();
+        char start1 = '{', start2 = '{', end1 = '}', end2 = '}';
+        int state = TEXT, startPos = 0, endPos = 0;
+        StringBuilder text = new StringBuilder();
+        int line = 0;
+
+        while (true) {
+            char c;
+            try {
+                int v = source.read();
+                if (v == -1) {
+                    break;
+                }
+                c = (char)v;
+            } catch (IOException e) {
+                throw new MustacheException(e);
+            }
+
+            if (c == '\n') {
+                line++;
+            }
+
+            switch (state) {
+            case TEXT:
+                if (c == start1) {
+                    if (start2 == -1) {
+                        accum.addTextSegment(text);
+                        state = TAG;
+                    } else {
+                        state = MATCHING_START;
+                    }
+                } else {
+                    text.append(c);
+                }
+                break;
+
+            case MATCHING_START:
+                if (c == start2) {
+                    accum.addTextSegment(text);
+                    state = TAG;
+                } else {
+                    text.append(start1);
+                    if (c != start1) {
+                        state = TEXT;
+                    }
+                }
+                break;
+
+            case TAG:
+                if (c == end1) {
+                    if (end2 == -1) {
+                        if (text.charAt(0) == '=') {
+                            // TODO: change delimiters
+                        } else {
+                            accum = accum.addTagSegment(text, line);
+                        }
+                        state = TEXT;
+                    } else {
+                        state = MATCHING_END;
+                    }
+                } else {
+                    text.append(c);
+                }
+                break;
+
+            case MATCHING_END:
+                if (c == end2) {
+                    if (text.charAt(0) == '=') {
+                        // TODO: change delimiters
+                    } else {
+                        accum = accum.addTagSegment(text, line);
+                    }
+                    state = TEXT;
+                } else {
+                    text.append(end1);
+                    if (c != end1) {
+                        state = TAG;
+                    }
+                }
+                break;
+            }
+        }
+
+        // accumulate any trailing text
+        switch (state) {
+        case TEXT:
+            accum.addTextSegment(text);
+            break;
+        case MATCHING_START:
+            text.append(start1);
+            accum.addTextSegment(text);
+            break;
+        case MATCHING_END:
+            text.append(end1);
+            accum.addTextSegment(text);
+            break;
+        case TAG:
+            throw new MustacheException("Template ended while parsing a tag TODO");
+        }
+
+        return new Template(accum.finish());
     }
 
     private Mustache () {} // no instantiateski
 
+    protected static String escapeHTML (String text)
+    {
+        for (int ii = 0; ii < ATTR_ESCAPES.length; ii++) {
+            text = text.replace(ATTR_ESCAPES[ii][0], ATTR_ESCAPES[ii][1]);
+        }
+        return text;
+    }
+
+    protected static final int TEXT = 0;
+    protected static final int MATCHING_START = 1;
+    protected static final int MATCHING_END = 2;
+    protected static final int TAG = 3;
+
+    protected static class Accumulator {
+        public void addTextSegment (StringBuilder text) {
+            if (text.length() > 0) {
+                _segs.add(new StringSegment(text.toString()));
+                text.setLength(0);
+            }
+        }
+
+        public Accumulator addTagSegment (StringBuilder accum, final int line) {
+            final Accumulator outer = this;
+            String tag = accum.toString().trim();
+            final String tag1 = tag.substring(1).trim();
+            accum.setLength(0);
+
+            switch (tag.charAt(0)) {
+            case '#':
+                requireNoNewlines(tag, line);
+                return new Accumulator() {
+                    public Template.Segment[] finish () {
+                        throw new MustacheException("Section missing close tag " +
+                                                    "[line=" + line + ", name=" + tag1 + "]");
+                    }
+                    protected Accumulator addCloseSectionSegment (String itag, int line) {
+                        requireSameName(tag1, itag, line);
+                        outer._segs.add(new SectionSegment(itag, super.finish()));
+                        return outer;
+                    }
+                };
+
+            case '^':
+                requireNoNewlines(tag, line);
+                return new Accumulator() {
+                    public Template.Segment[] finish () {
+                        throw new MustacheException("Inverted section missing close tag " +
+                                                    "[line=" + line + ", name=" + tag1 + "]");
+                    }
+                    protected Accumulator addCloseSectionSegment (String itag, int line) {
+                        requireSameName(tag1, itag, line);
+                        outer._segs.add(new InvertedSectionSegment(itag, super.finish()));
+                        return outer;
+                    }
+                };
+
+            case '/':
+                requireNoNewlines(tag, line);
+                return addCloseSectionSegment(tag1, line);
+
+            case '!':
+                // comment!, ignore
+                return this;
+
+            case '&':
+                requireNoNewlines(tag, line);
+                _segs.add(new VariableSegment(tag1, false));
+                return this;
+
+            default:
+                requireNoNewlines(tag, line);
+                _segs.add(new VariableSegment(tag, true));
+                return this;
+            }
+        }
+
+        public Template.Segment[] finish () {
+            return _segs.toArray(new Template.Segment[_segs.size()]);
+        }
+
+        protected Accumulator addCloseSectionSegment (String tag, int line) {
+            throw new MustacheException("Section close tag with no open tag " +
+                                        "[line=" + line + ", name=" + tag + "]");
+        }
+
+        protected static void requireNoNewlines (String tag, int line) {
+            if (tag.indexOf("\n") != -1 || tag.indexOf("\r") != -1) {
+                throw new MustacheException("Invalid tag name: contains newlne " +
+                                            "[line=" + line + ", name=" + tag + "]");
+            }
+        }
+
+        protected static void requireSameName (String name1, String name2, int line)
+        {
+            if (!name1.equals(name2)) {
+                throw new MustacheException(
+                    "Section close tag with mismatched open tag " +
+                    "[line=" + line + ", expected=" + name1 + ", got=" + name2 + "]");
+            }
+        }
+
+        protected final List<Template.Segment> _segs = new ArrayList<Template.Segment>();
+    }
+
     /** A simple segment that reproduces a string. */
     protected static class StringSegment extends Template.Segment {
         public StringSegment (String text) {
             _text = text;
         }
-
         @Override public void execute (Object ctx, Writer out) {
             write(out, _text);
         }
-
         protected final String _text;
     }
 
-    /** A segment that substitutes the contents of a variable. */
+    /** A helper class for named segments. */
-    protected static class VariableSegment extends Template.Segment {
+    protected static abstract class NamedSegment extends Template.Segment {
-        public VariableSegment (String name) {
+        protected NamedSegment (String name) {
             _name = name;
         }
+        protected final String _name;
+    }
 
+    /** A segment that substitutes the contents of a variable. */
+    protected static class VariableSegment extends NamedSegment {
+        public VariableSegment (String name, boolean escapeHTML) {
+            super(name);
+            _escapeHTML = escapeHTML;
+        }
         @Override public void execute (Object ctx, Writer out)  {
             Object value = getValue(ctx, _name);
             // TODO: configurable behavior on missing values
             if (value != null) {
-                write(out, String.valueOf(value));
+                String text = String.valueOf(value);
+                write(out, _escapeHTML ? escapeHTML(text) : text);
             }
         }
+        protected boolean _escapeHTML;
+    }
 
-        protected final String _name;
+    /** A helper class for compound segments. */
+    protected static abstract class CompoundSegment extends NamedSegment {
+        protected CompoundSegment (String name, Template.Segment[] segs) {
+            super(name);
+            _segs = segs;
+        }
+        protected void executeSegs (Object ctx, Writer out)  {
+            for (Template.Segment seg : _segs) {
+                seg.execute(ctx, out);
+            }
+        }
+        protected final Template.Segment[] _segs;
     }
 
     /** A segment that represents a section. */
-    protected static class SectionSegment extends Template.Segment {
+    protected static class SectionSegment extends CompoundSegment {
         public SectionSegment (String name, Template.Segment[] segs) {
-            _name = name;
+            super(name, segs);
-            _segs = segs;
         }
-
         @Override public void execute (Object ctx, Writer out)  {
             Object value = getValue(ctx, _name);
             if (value == null) {
@@ -97,14 +328,47 @@ public class Mustache
                 executeSegs(value, out);
             }
         }
+    }
 
-        protected void executeSegs (Object ctx, Writer out)  {
+    /** A segment that represents an inverted section. */
-            for (Template.Segment seg : _segs) {
+    protected static class InvertedSectionSegment extends CompoundSegment {
-                seg.execute(ctx, out);
+        public InvertedSectionSegment (String name, Template.Segment[] segs) {
+            super(name, segs);
+        }
+        @Override public void execute (Object ctx, Writer out)  {
+            Object value = getValue(ctx, _name);
+            if (value == null) {
+                executeSegs(ctx, out); // TODO: configurable behavior on missing values
+            }
+            if (value instanceof Iterable<?>) {
+                Iterable<?> iable = (Iterable<?>)value;
+                if (!iable.iterator().hasNext()) {
+                    executeSegs(ctx, out);
+                }
+            } else if (value instanceof Boolean) {
+                if (!(Boolean)value) {
+                    executeSegs(ctx, out);
+                }
+            } else if (value.getClass().isArray()) {
+                if (Array.getLength(value) == 0) {
+                    executeSegs(ctx, out);
+                }
+            } else if (value instanceof Iterator<?>) {
+                Iterator<?> iter = (Iterator<?>)value;
+                if (!iter.hasNext()) {
+                    executeSegs(ctx, out);
+                }
             }
         }
-
-        protected String _name;
-        protected Template.Segment[] _segs;
     }
+
+    /** Map of strings that must be replaced inside html attributes and their replacements. (They
+     * need to be applied in order so amps are not double escaped.) */
+    protected static final String[][] ATTR_ESCAPES = {
+        { "&", "&amp;" },
+        { "'", "&apos;" },
+        { "\"", "&quot;" },
+        { "<", "&lt;" },
+        { ">", "&gt;" },
+    };
 }

src/test/java/com/samskivert/mustache/MustacheTest.java

@@ -0,0 +1,81 @@
+//
+// $Id$
+
+package com.samskivert.mustache;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
+import org.junit.*;
+import static org.junit.Assert.*;
+
+/**
+ * Various unit tests.
+ */
+public class MustacheTest
+{
+    @Test public void testSimpleVariable () {
+        test("bar", "{{foo}}", "foo", "bar");
+    }
+
+    @Test public void testOneShotSection () {
+        test("baz", "{{#foo}}{{bar}}{{/foo}}", "foo", context("bar", "baz"));
+    }
+
+    @Test public void testListSection () {
+        test("bazbif", "{{#foo}}{{bar}}{{/foo}}", "foo",
+             Arrays.asList(context("bar", "baz"), context("bar", "bif")));
+    }
+
+    @Test public void testArraySection () {
+        test("bazbif", "{{#foo}}{{bar}}{{/foo}}", "foo",
+             new Object[] { context("bar", "baz"), context("bar", "bif") });
+    }
+
+    @Test public void testIteratorSection () {
+        test("bazbif", "{{#foo}}{{bar}}{{/foo}}", "foo",
+             Arrays.asList(context("bar", "baz"), context("bar", "bif")).iterator());
+    }
+
+    @Test public void testEmptyListSection () {
+        test("", "{{#foo}}{{bar}}{{/foo}}", "foo", Collections.emptyList());
+    }
+
+    @Test public void testEmptyArraySection () {
+        test("", "{{#foo}}{{bar}}{{/foo}}", "foo", new Object[0]);
+    }
+
+    @Test public void testEmptyIteratorSection () {
+        test("", "{{#foo}}{{bar}}{{/foo}}", "foo", Collections.emptyList().iterator());
+    }
+
+    @Test public void testFalseSection () {
+        test("", "{{#foo}}{{bar}}{{/foo}}", "foo", false);
+    }
+
+    @Test public void testNestedListSection () {
+        test("1234", "{{#a}}{{#b}}{{c}}{{/b}}{{#d}}{{e}}{{/d}}{{/a}}", "a",
+             new Object[] { context("b", new Object[] { context("c", "1"), context("c", "2") }),
+                            context("d", new Object[] { context("e", "3"), context("e", "4") }) });
+    }
+
+    @Test public void testComment () {
+        test("foobar", "foo{{! nothing to see here}}bar");
+    }
+
+    protected void test (String expected, String template, Object... data)
+    {
+        assertEquals(expected, Mustache.compile(template).execute(context(data)));
+    }
+
+    protected static Object context (Object... data)
+    {
+        Map<String, Object> ctx = new HashMap<String, Object>();
+        for (int ii = 0; ii < data.length; ii += 2) {
+            ctx.put(data[ii].toString(), data[ii+1]);
+        }
+        return ctx;
+    }
+}