Updating merge isuse.

I had an idea to try and merge the lexer and the parser.  It is, after
all, a PEG-generated lexer, and PEGs are supposed to generate parsers,
right?  But the elegance of the separation at this point is so nice and
straightforward that I don't think I win anything by merging them.

.gitignore

@@ -4,5 +4,6 @@
 *.orig
 npm-debug.log
 node_modules/*
-lib/
 tmp/
+src/*.js
+lib/*.js

Makefile

@@ -22,7 +22,7 @@ lib:
 
 $(cof_objects): $(cof_sources)
 	@mkdir -p $(@D)
-	$(COFFEE) -o $(@D) -c $<
+	$(foreach source, $(cof_sources), $(COFFEE) -o $(@D) -c $(source); )
 
 $(peg_objects): $(peg_sources)
 	@mkdir -p $(@D)

README.md

@@ -36,10 +36,13 @@ a string or a number.
 ### If
 
 An "if:<name>" section can contain other objects, but the entirety of
-the section is only rendered if the current context scope contains the
-current name, and the value associated with that name is "true" in a
-boolean context.  You might use to show someone's name, if the name
-field is populated, and show nothing if it isn't.
+the section is only rendered if the current context scope, and *only*
+the current context scope, contains the current name, and the value
+associated with that name is "true" in a boolean context.  You might
+use to show someone's name, if the name field is populated, and show
+nothing if it isn't.  This is useful for detecting if the current
+context has a field, but you don't want previous contexts' synonyms
+showing up.
 
 If your datasource returns:
 
@@ -49,6 +52,12 @@ Then your template would use:
 
     {if:name}Hello {name}!{/if:name}
 
+### When
+
+A "when:<name>" section is the same as the "if", but it will render if
+the current context scope, and any previous context scope on the
+stack, contains the current name.
+
 ### Block
 
 A "block:<name>" section can contain other objects, but the entirety

lib/engine.js

@@ -0,0 +1,37 @@
+// Generated by CoffeeScript 1.6.1
+(function() {
+  var fromFile, fs, parse, render, tumble;
+
+  tumble = require('./lexer').parse;
+
+  parse = require('./parser');
+
+  fs = require('fs');
+
+  render = function(str, options, callback) {
+    try {
+      return callback(null, parse(tumble(str), options));
+    } catch (err) {
+      return callback(err, null);
+    }
+  };
+
+  fromFile = function(path, options, callback) {
+    return fs.readFile(path, 'utf8', function(err, str) {
+      if (callback) {
+        if (err) {
+          return callback(err);
+        }
+        return callback(null, render(str, options, callback));
+      }
+      if (err) {
+        throw err;
+      }
+    });
+  };
+
+  fromFile.render = render;
+
+  module.exports = fromFile;
+
+}).call(this);

lib/lexer.js

@@ -0,0 +1,850 @@
+module.exports = (function() {
+  /*
+   * Generated by PEG.js 0.7.0.
+   *
+   * http://pegjs.majda.cz/
+   */
+
+  function peg$subclass(child, parent) {
+    function ctor() { this.constructor = child; }
+    ctor.prototype = parent.prototype;
+    child.prototype = new ctor();
+  }
+
+  function SyntaxError(expected, found, offset, line, column) {
+    function buildMessage(expected, found) {
+      function stringEscape(s) {
+        function hex(ch) { return ch.charCodeAt(0).toString(16).toUpperCase(); }
+
+        return s
+          .replace(/\\/g,   '\\\\')
+          .replace(/"/g,    '\\"')
+          .replace(/\x08/g, '\\b')
+          .replace(/\t/g,   '\\t')
+          .replace(/\n/g,   '\\n')
+          .replace(/\f/g,   '\\f')
+          .replace(/\r/g,   '\\r')
+          .replace(/[\x00-\x07\x0B\x0E\x0F]/g, function(ch) { return '\\x0' + hex(ch); })
+          .replace(/[\x10-\x1F\x80-\xFF]/g,    function(ch) { return '\\x'  + hex(ch); })
+          .replace(/[\u0180-\u0FFF]/g,         function(ch) { return '\\u0' + hex(ch); })
+          .replace(/[\u1080-\uFFFF]/g,         function(ch) { return '\\u'  + hex(ch); });
+      }
+
+      var expectedDesc, foundDesc;
+
+      switch (expected.length) {
+        case 0:
+          expectedDesc = "end of input";
+          break;
+
+        case 1:
+          expectedDesc = expected[0];
+          break;
+
+        default:
+          expectedDesc = expected.slice(0, -1).join(", ")
+            + " or "
+            + expected[expected.length - 1];
+      }
+
+      foundDesc = found ? "\"" + stringEscape(found) + "\"" : "end of input";
+
+      return "Expected " + expectedDesc + " but " + foundDesc + " found.";
+    }
+
+    this.expected = expected;
+    this.found    = found;
+    this.offset   = offset;
+    this.line     = line;
+    this.column   = column;
+
+    this.name     = "SyntaxError";
+    this.message  = buildMessage(expected, found);
+  }
+
+  peg$subclass(SyntaxError, Error);
+
+  function parse(input) {
+    var options = arguments.length > 1 ? arguments[1] : {},
+
+        peg$startRuleFunctions = { document: peg$parsedocument },
+        peg$startRuleFunction  = peg$parsedocument,
+
+        peg$c0 = [],
+        peg$c1 = function(ps) { return { unit: "block", name: "document", content: ps }; },
+        peg$c2 = "tag_start",
+        peg$c3 = null,
+        peg$c4 = ":",
+        peg$c5 = "\":\"",
+        peg$c6 = function(b, n) { return is_valid_block_type(b); },
+        peg$c7 = "",
+        peg$c8 = function(b, n) { return {type: b, name: n }; },
+        peg$c9 = "/",
+        peg$c10 = "\"/\"",
+        peg$c11 = "tagname",
+        peg$c12 = /^[a-zA-Z]/,
+        peg$c13 = "[a-zA-Z]",
+        peg$c14 = function(t) { return t.join(''); },
+        peg$c15 = /^[a-zA-Z:\/]/,
+        peg$c16 = "[a-zA-Z:\\/]",
+        peg$c17 = "{",
+        peg$c18 = "\"{\"",
+        peg$c19 = "}",
+        peg$c20 = "\"}\"",
+        peg$c21 = "\n",
+        peg$c22 = "\"\\n\"",
+        peg$c23 = "\r\n",
+        peg$c24 = "\"\\r\\n\"",
+        peg$c25 = "\r",
+        peg$c26 = "\"\\r\"",
+        peg$c27 = "\u2028",
+        peg$c28 = "\"\\u2028\"",
+        peg$c29 = "\u2029",
+        peg$c30 = "\"\\u2029\"",
+        peg$c31 = "any character",
+        peg$c32 = function(c) {return c},
+        peg$c33 = function(bs) { return { unit: 'text', content: bs.join('') } },
+        peg$c34 = "variable",
+        peg$c35 = function(t) { return { unit: 'variable', name: t }; },
+        peg$c36 = function(t, ps, n) { return (t.type == n.type) && (t.name == n.name) },
+        peg$c37 = function(t, ps, n) { return {unit: 'block', type:t.type, name:t.name, content: ps } },
+
+        peg$currPos          = 0,
+        peg$reportedPos      = 0,
+        peg$cachedPos        = 0,
+        peg$cachedPosDetails = { line: 1, column: 1, seenCR: false },
+        peg$maxFailPos       = 0,
+        peg$maxFailExpected  = [],
+        peg$silentFails      = 0,
+
+        peg$result;
+
+    if ("startRule" in options) {
+      if (!(options.startRule in peg$startRuleFunctions)) {
+        throw new Error("Can't start parsing from rule \"" + options.startRule + "\".");
+      }
+
+      peg$startRuleFunction = peg$startRuleFunctions[options.startRule];
+    }
+
+    function text() {
+      return input.substring(peg$reportedPos, peg$currPos);
+    }
+
+    function offset() {
+      return peg$reportedPos;
+    }
+
+    function line() {
+      return peg$computePosDetails(peg$reportedPos).line;
+    }
+
+    function column() {
+      return peg$computePosDetails(peg$reportedPos).column;
+    }
+
+    function peg$computePosDetails(pos) {
+      function advance(details, startPos, endPos) {
+        var p, ch;
+
+        for (p = startPos; p < endPos; p++) {
+          ch = input.charAt(p);
+          if (ch === "\n") {
+            if (!details.seenCR) { details.line++; }
+            details.column = 1;
+            details.seenCR = false;
+          } else if (ch === "\r" || ch === "\u2028" || ch === "\u2029") {
+            details.line++;
+            details.column = 1;
+            details.seenCR = true;
+          } else {
+            details.column++;
+            details.seenCR = false;
+          }
+        }
+      }
+
+      if (peg$cachedPos !== pos) {
+        if (peg$cachedPos > pos) {
+          peg$cachedPos = 0;
+          peg$cachedPosDetails = { line: 1, column: 1, seenCR: false };
+        }
+        advance(peg$cachedPosDetails, peg$cachedPos, pos);
+        peg$cachedPos = pos;
+      }
+
+      return peg$cachedPosDetails;
+    }
+
+    function peg$fail(expected) {
+      if (peg$currPos < peg$maxFailPos) { return; }
+
+      if (peg$currPos > peg$maxFailPos) {
+        peg$maxFailPos = peg$currPos;
+        peg$maxFailExpected = [];
+      }
+
+      peg$maxFailExpected.push(expected);
+    }
+
+    function peg$cleanupExpected(expected) {
+      var i = 0;
+
+      expected.sort();
+
+      while (i < expected.length) {
+        if (expected[i - 1] === expected[i]) {
+          expected.splice(i, 1);
+        } else {
+          i++;
+        }
+      }
+    }
+
+    function peg$parsedocument() {
+      var s0, s1, s2;
+
+      s0 = peg$currPos;
+      s1 = [];
+      s2 = peg$parsepart();
+      while (s2 !== null) {
+        s1.push(s2);
+        s2 = peg$parsepart();
+      }
+      if (s1 !== null) {
+        peg$reportedPos = s0;
+        s1 = peg$c1(s1);
+      }
+      if (s1 === null) {
+        peg$currPos = s0;
+        s0 = s1;
+      } else {
+        s0 = s1;
+      }
+
+      return s0;
+    }
+
+    function peg$parsepart() {
+      var s0;
+
+      s0 = peg$parseblock();
+      if (s0 === null) {
+        s0 = peg$parsevariable();
+        if (s0 === null) {
+          s0 = peg$parsetext();
+        }
+      }
+
+      return s0;
+    }
+
+    function peg$parsetag_start() {
+      var s0, s1, s2, s3, s4, s5, s6;
+
+      peg$silentFails++;
+      s0 = peg$currPos;
+      s1 = peg$parseld();
+      if (s1 !== null) {
+        s2 = peg$parsetagname();
+        if (s2 !== null) {
+          if (input.charCodeAt(peg$currPos) === 58) {
+            s3 = peg$c4;
+            peg$currPos++;
+          } else {
+            s3 = null;
+            if (peg$silentFails === 0) { peg$fail(peg$c5); }
+          }
+          if (s3 !== null) {
+            s4 = peg$parsetagname();
+            if (s4 !== null) {
+              s5 = peg$parserd();
+              if (s5 !== null) {
+                peg$reportedPos = peg$currPos;
+                s6 = peg$c6(s2,s4);
+                if (s6) {
+                  s6 = peg$c7;
+                } else {
+                  s6 = peg$c3;
+                }
+                if (s6 !== null) {
+                  peg$reportedPos = s0;
+                  s1 = peg$c8(s2,s4);
+                  if (s1 === null) {
+                    peg$currPos = s0;
+                    s0 = s1;
+                  } else {
+                    s0 = s1;
+                  }
+                } else {
+                  peg$currPos = s0;
+                  s0 = peg$c3;
+                }
+              } else {
+                peg$currPos = s0;
+                s0 = peg$c3;
+              }
+            } else {
+              peg$currPos = s0;
+              s0 = peg$c3;
+            }
+          } else {
+            peg$currPos = s0;
+            s0 = peg$c3;
+          }
+        } else {
+          peg$currPos = s0;
+          s0 = peg$c3;
+        }
+      } else {
+        peg$currPos = s0;
+        s0 = peg$c3;
+      }
+      peg$silentFails--;
+      if (s0 === null) {
+        s1 = null;
+        if (peg$silentFails === 0) { peg$fail(peg$c2); }
+      }
+
+      return s0;
+    }
+
+    function peg$parsetag_end() {
+      var s0, s1, s2, s3, s4, s5, s6;
+
+      s0 = peg$currPos;
+      s1 = peg$parseld();
+      if (s1 !== null) {
+        if (input.charCodeAt(peg$currPos) === 47) {
+          s2 = peg$c9;
+          peg$currPos++;
+        } else {
+          s2 = null;
+          if (peg$silentFails === 0) { peg$fail(peg$c10); }
+        }
+        if (s2 !== null) {
+          s3 = peg$parsetagname();
+          if (s3 !== null) {
+            if (input.charCodeAt(peg$currPos) === 58) {
+              s4 = peg$c4;
+              peg$currPos++;
+            } else {
+              s4 = null;
+              if (peg$silentFails === 0) { peg$fail(peg$c5); }
+            }
+            if (s4 !== null) {
+              s5 = peg$parsetagname();
+              if (s5 !== null) {
+                s6 = peg$parserd();
+                if (s6 !== null) {
+                  peg$reportedPos = s0;
+                  s1 = peg$c8(s3,s5);
+                  if (s1 === null) {
+                    peg$currPos = s0;
+                    s0 = s1;
+                  } else {
+                    s0 = s1;
+                  }
+                } else {
+                  peg$currPos = s0;
+                  s0 = peg$c3;
+                }
+              } else {
+                peg$currPos = s0;
+                s0 = peg$c3;
+              }
+            } else {
+              peg$currPos = s0;
+              s0 = peg$c3;
+            }
+          } else {
+            peg$currPos = s0;
+            s0 = peg$c3;
+          }
+        } else {
+          peg$currPos = s0;
+          s0 = peg$c3;
+        }
+      } else {
+        peg$currPos = s0;
+        s0 = peg$c3;
+      }
+
+      return s0;
+    }
+
+    function peg$parsetagname() {
+      var s0, s1, s2;
+
+      peg$silentFails++;
+      s0 = peg$currPos;
+      s1 = [];
+      if (peg$c12.test(input.charAt(peg$currPos))) {
+        s2 = input.charAt(peg$currPos);
+        peg$currPos++;
+      } else {
+        s2 = null;
+        if (peg$silentFails === 0) { peg$fail(peg$c13); }
+      }
+      if (s2 !== null) {
+        while (s2 !== null) {
+          s1.push(s2);
+          if (peg$c12.test(input.charAt(peg$currPos))) {
+            s2 = input.charAt(peg$currPos);
+            peg$currPos++;
+          } else {
+            s2 = null;
+            if (peg$silentFails === 0) { peg$fail(peg$c13); }
+          }
+        }
+      } else {
+        s1 = peg$c3;
+      }
+      if (s1 !== null) {
+        peg$reportedPos = s0;
+        s1 = peg$c14(s1);
+      }
+      if (s1 === null) {
+        peg$currPos = s0;
+        s0 = s1;
+      } else {
+        s0 = s1;
+      }
+      peg$silentFails--;
+      if (s0 === null) {
+        s1 = null;
+        if (peg$silentFails === 0) { peg$fail(peg$c11); }
+      }
+
+      return s0;
+    }
+
+    function peg$parsetag() {
+      var s0, s1, s2, s3, s4, s5, s6;
+
+      s0 = peg$currPos;
+      s1 = peg$parseld();
+      if (s1 !== null) {
+        s2 = [];
+        s3 = peg$currPos;
+        s4 = peg$currPos;
+        peg$silentFails++;
+        s5 = peg$parserd();
+        peg$silentFails--;
+        if (s5 === null) {
+          s4 = peg$c7;
+        } else {
+          peg$currPos = s4;
+          s4 = peg$c3;
+        }
+        if (s4 !== null) {
+          s5 = peg$currPos;
+          peg$silentFails++;
+          s6 = peg$parseeol();
+          peg$silentFails--;
+          if (s6 === null) {
+            s5 = peg$c7;
+          } else {
+            peg$currPos = s5;
+            s5 = peg$c3;
+          }
+          if (s5 !== null) {
+            if (peg$c15.test(input.charAt(peg$currPos))) {
+              s6 = input.charAt(peg$currPos);
+              peg$currPos++;
+            } else {
+              s6 = null;
+              if (peg$silentFails === 0) { peg$fail(peg$c16); }
+            }
+            if (s6 !== null) {
+              s4 = [s4, s5, s6];
+              s3 = s4;
+            } else {
+              peg$currPos = s3;
+              s3 = peg$c3;
+            }
+          } else {
+            peg$currPos = s3;
+            s3 = peg$c3;
+          }
+        } else {
+          peg$currPos = s3;
+          s3 = peg$c3;
+        }
+        if (s3 !== null) {
+          while (s3 !== null) {
+            s2.push(s3);
+            s3 = peg$currPos;
+            s4 = peg$currPos;
+            peg$silentFails++;
+            s5 = peg$parserd();
+            peg$silentFails--;
+            if (s5 === null) {
+              s4 = peg$c7;
+            } else {
+              peg$currPos = s4;
+              s4 = peg$c3;
+            }
+            if (s4 !== null) {
+              s5 = peg$currPos;
+              peg$silentFails++;
+              s6 = peg$parseeol();
+              peg$silentFails--;
+              if (s6 === null) {
+                s5 = peg$c7;
+              } else {
+                peg$currPos = s5;
+                s5 = peg$c3;
+              }
+              if (s5 !== null) {
+                if (peg$c15.test(input.charAt(peg$currPos))) {
+                  s6 = input.charAt(peg$currPos);
+                  peg$currPos++;
+                } else {
+                  s6 = null;
+                  if (peg$silentFails === 0) { peg$fail(peg$c16); }
+                }
+                if (s6 !== null) {
+                  s4 = [s4, s5, s6];
+                  s3 = s4;
+                } else {
+                  peg$currPos = s3;
+                  s3 = peg$c3;
+                }
+              } else {
+                peg$currPos = s3;
+                s3 = peg$c3;
+              }
+            } else {
+              peg$currPos = s3;
+              s3 = peg$c3;
+            }
+          }
+        } else {
+          s2 = peg$c3;
+        }
+        if (s2 !== null) {
+          s3 = peg$parserd();
+          if (s3 !== null) {
+            s1 = [s1, s2, s3];
+            s0 = s1;
+          } else {
+            peg$currPos = s0;
+            s0 = peg$c3;
+          }
+        } else {
+          peg$currPos = s0;
+          s0 = peg$c3;
+        }
+      } else {
+        peg$currPos = s0;
+        s0 = peg$c3;
+      }
+
+      return s0;
+    }
+
+    function peg$parseld() {
+      var s0;
+
+      if (input.charCodeAt(peg$currPos) === 123) {
+        s0 = peg$c17;
+        peg$currPos++;
+      } else {
+        s0 = null;
+        if (peg$silentFails === 0) { peg$fail(peg$c18); }
+      }
+
+      return s0;
+    }
+
+    function peg$parserd() {
+      var s0;
+
+      if (input.charCodeAt(peg$currPos) === 125) {
+        s0 = peg$c19;
+        peg$currPos++;
+      } else {
+        s0 = null;
+        if (peg$silentFails === 0) { peg$fail(peg$c20); }
+      }
+
+      return s0;
+    }
+
+    function peg$parseeol() {
+      var s0;
+
+      if (input.charCodeAt(peg$currPos) === 10) {
+        s0 = peg$c21;
+        peg$currPos++;
+      } else {
+        s0 = null;
+        if (peg$silentFails === 0) { peg$fail(peg$c22); }
+      }
+      if (s0 === null) {
+        if (input.substr(peg$currPos, 2) === peg$c23) {
+          s0 = peg$c23;
+          peg$currPos += 2;
+        } else {
+          s0 = null;
+          if (peg$silentFails === 0) { peg$fail(peg$c24); }
+        }
+        if (s0 === null) {
+          if (input.charCodeAt(peg$currPos) === 13) {
+            s0 = peg$c25;
+            peg$currPos++;
+          } else {
+            s0 = null;
+            if (peg$silentFails === 0) { peg$fail(peg$c26); }
+          }
+          if (s0 === null) {
+            if (input.charCodeAt(peg$currPos) === 8232) {
+              s0 = peg$c27;
+              peg$currPos++;
+            } else {
+              s0 = null;
+              if (peg$silentFails === 0) { peg$fail(peg$c28); }
+            }
+            if (s0 === null) {
+              if (input.charCodeAt(peg$currPos) === 8233) {
+                s0 = peg$c29;
+                peg$currPos++;
+              } else {
+                s0 = null;
+                if (peg$silentFails === 0) { peg$fail(peg$c30); }
+              }
+            }
+          }
+        }
+      }
+
+      return s0;
+    }
+
+    function peg$parsetext() {
+      var s0, s1, s2, s3, s4;
+
+      s0 = peg$currPos;
+      s1 = [];
+      s2 = peg$currPos;
+      s3 = peg$currPos;
+      peg$silentFails++;
+      s4 = peg$parsetag();
+      peg$silentFails--;
+      if (s4 === null) {
+        s3 = peg$c7;
+      } else {
+        peg$currPos = s3;
+        s3 = peg$c3;
+      }
+      if (s3 !== null) {
+        if (input.length > peg$currPos) {
+          s4 = input.charAt(peg$currPos);
+          peg$currPos++;
+        } else {
+          s4 = null;
+          if (peg$silentFails === 0) { peg$fail(peg$c31); }
+        }
+        if (s4 !== null) {
+          peg$reportedPos = s2;
+          s3 = peg$c32(s4);
+          if (s3 === null) {
+            peg$currPos = s2;
+            s2 = s3;
+          } else {
+            s2 = s3;
+          }
+        } else {
+          peg$currPos = s2;
+          s2 = peg$c3;
+        }
+      } else {
+        peg$currPos = s2;
+        s2 = peg$c3;
+      }
+      if (s2 !== null) {
+        while (s2 !== null) {
+          s1.push(s2);
+          s2 = peg$currPos;
+          s3 = peg$currPos;
+          peg$silentFails++;
+          s4 = peg$parsetag();
+          peg$silentFails--;
+          if (s4 === null) {
+            s3 = peg$c7;
+          } else {
+            peg$currPos = s3;
+            s3 = peg$c3;
+          }
+          if (s3 !== null) {
+            if (input.length > peg$currPos) {
+              s4 = input.charAt(peg$currPos);
+              peg$currPos++;
+            } else {
+              s4 = null;
+              if (peg$silentFails === 0) { peg$fail(peg$c31); }
+            }
+            if (s4 !== null) {
+              peg$reportedPos = s2;
+              s3 = peg$c32(s4);
+              if (s3 === null) {
+                peg$currPos = s2;
+                s2 = s3;
+              } else {
+                s2 = s3;
+              }
+            } else {
+              peg$currPos = s2;
+              s2 = peg$c3;
+            }
+          } else {
+            peg$currPos = s2;
+            s2 = peg$c3;
+          }
+        }
+      } else {
+        s1 = peg$c3;
+      }
+      if (s1 !== null) {
+        peg$reportedPos = s0;
+        s1 = peg$c33(s1);
+      }
+      if (s1 === null) {
+        peg$currPos = s0;
+        s0 = s1;
+      } else {
+        s0 = s1;
+      }
+
+      return s0;
+    }
+
+    function peg$parsevariable() {
+      var s0, s1, s2, s3;
+
+      peg$silentFails++;
+      s0 = peg$currPos;
+      s1 = peg$parseld();
+      if (s1 !== null) {
+        s2 = peg$parsetagname();
+        if (s2 !== null) {
+          s3 = peg$parserd();
+          if (s3 !== null) {
+            peg$reportedPos = s0;
+            s1 = peg$c35(s2);
+            if (s1 === null) {
+              peg$currPos = s0;
+              s0 = s1;
+            } else {
+              s0 = s1;
+            }
+          } else {
+            peg$currPos = s0;
+            s0 = peg$c3;
+          }
+        } else {
+          peg$currPos = s0;
+          s0 = peg$c3;
+        }
+      } else {
+        peg$currPos = s0;
+        s0 = peg$c3;
+      }
+      peg$silentFails--;
+      if (s0 === null) {
+        s1 = null;
+        if (peg$silentFails === 0) { peg$fail(peg$c34); }
+      }
+
+      return s0;
+    }
+
+    function peg$parseblock() {
+      var s0, s1, s2, s3, s4;
+
+      s0 = peg$currPos;
+      s1 = peg$parsetag_start();
+      if (s1 !== null) {
+        s2 = [];
+        s3 = peg$parsepart();
+        while (s3 !== null) {
+          s2.push(s3);
+          s3 = peg$parsepart();
+        }
+        if (s2 !== null) {
+          s3 = peg$parsetag_end();
+          if (s3 !== null) {
+            peg$reportedPos = peg$currPos;
+            s4 = peg$c36(s1,s2,s3);
+            if (s4) {
+              s4 = peg$c7;
+            } else {
+              s4 = peg$c3;
+            }
+            if (s4 !== null) {
+              peg$reportedPos = s0;
+              s1 = peg$c37(s1,s2,s3);
+              if (s1 === null) {
+                peg$currPos = s0;
+                s0 = s1;
+              } else {
+                s0 = s1;
+              }
+            } else {
+              peg$currPos = s0;
+              s0 = peg$c3;
+            }
+          } else {
+            peg$currPos = s0;
+            s0 = peg$c3;
+          }
+        } else {
+          peg$currPos = s0;
+          s0 = peg$c3;
+        }
+      } else {
+        peg$currPos = s0;
+        s0 = peg$c3;
+      }
+
+      return s0;
+    }
+
+
+        var _VALID_BLOCK_TYPES = ['if', 'when', 'template', 'many', 'block'];
+        var _VBT_LENGTH = _VALID_BLOCK_TYPES.length;
+
+        function is_valid_block_type(b) {
+            for(var i = 0; i < _VBT_LENGTH; i++) {
+                if (_VALID_BLOCK_TYPES[i] == b) {
+                    return true;
+                }
+            }
+            return false;
+        }
+
+
+    peg$result = peg$startRuleFunction();
+
+    if (peg$result !== null && peg$currPos === input.length) {
+      return peg$result;
+    } else {
+      peg$cleanupExpected(peg$maxFailExpected);
+      peg$reportedPos = Math.max(peg$currPos, peg$maxFailPos);
+
+      throw new SyntaxError(
+        peg$maxFailExpected,
+        peg$reportedPos < input.length ? input.charAt(peg$reportedPos) : null,
+        peg$reportedPos,
+        peg$computePosDetails(peg$reportedPos).line,
+        peg$computePosDetails(peg$reportedPos).column
+      );
+    }
+  }
+
+  return {
+    SyntaxError: SyntaxError,
+    parse      : parse
+  };
+})();

lib/parser.js

@@ -0,0 +1,174 @@
+// Generated by CoffeeScript 1.6.1
+(function() {
+  var Contexter, _;
+
+  _ = require('underscore');
+
+  Contexter = (function() {
+
+    function Contexter(content) {
+      this.content = content;
+      this.stack = [this.content];
+      this.templates = {};
+      this.depth = 0;
+    }
+
+    Contexter.prototype.has_any = function(name) {
+      return _.find(this.stack, function(o) {
+        return _.has(o, name);
+      });
+    };
+
+    Contexter.prototype.has_any_one = function(name) {
+      var p;
+      p = this.has_any(name);
+      if (p) {
+        return p[name];
+      } else {
+        return null;
+      }
+    };
+
+    Contexter.prototype.has = function(name) {
+      if (this.stack[0][name] != null) {
+        return this.stack[0][name];
+      } else {
+        return null;
+      }
+    };
+
+    Contexter.prototype.get = function(name, alt) {
+      var p;
+      if (alt == null) {
+        alt = '';
+      }
+      p = this.has_any_one(name);
+      if (p && (_.isString(p) || _.isNumber(p))) {
+        return p;
+      }
+      return this.render(name);
+    };
+
+    Contexter.prototype.once = function(obj, cb) {
+      var r;
+      this.stack.unshift(obj);
+      this.depth++;
+      if (this.depth > 10) {
+        throw new Error('recursion-error');
+      }
+      r = cb(this);
+      this.stack.shift();
+      this.depth--;
+      return r;
+    };
+
+    Contexter.prototype.when = function(name, cb) {
+      var p;
+      p = this.has_any_one(name);
+      if (p) {
+        return cb(this);
+      } else {
+        return '';
+      }
+    };
+
+    Contexter.prototype["if"] = function(name, cb) {
+      var p;
+      p = this.has(name);
+      if (p) {
+        return cb(this);
+      } else {
+        return '';
+      }
+    };
+
+    Contexter.prototype.block = function(name, cb) {
+      var p;
+      p = this.has_any_one(name);
+      if (p && _.isObject(p)) {
+        return this.once(p, cb);
+      } else {
+        return '';
+      }
+    };
+
+    Contexter.prototype.many = function(name, cb) {
+      var ps,
+        _this = this;
+      ps = this.has(name);
+      if (!(ps && _.isArray(ps))) {
+        return "";
+      }
+      return (_.map(ps, function(p) {
+        return _this.once(p, cb);
+      })).join('');
+    };
+
+    Contexter.prototype.template = function(name, cb) {
+      this.templates[name] = cb;
+      return "";
+    };
+
+    Contexter.prototype.render = function(name) {
+      var ret;
+      if ((this.templates[name] != null) && _.isFunction(this.templates[name])) {
+        this.depth++;
+        if (this.depth > 10) {
+          throw new Error('recursion-error');
+        }
+        ret = this.templates[name](this);
+        this.depth--;
+        return ret;
+      } else {
+        return "";
+      }
+    };
+
+    return Contexter;
+
+  })();
+
+  module.exports = function(ast, data) {
+    var cmd, context, o;
+    context = new Contexter(data);
+    cmd = function(o) {
+      switch (o.unit) {
+        case 'variable':
+          return function(context) {
+            return context.get(o.name);
+          };
+        case 'text':
+          return function(context) {
+            return o.content;
+          };
+        case 'block':
+          return function(context) {
+            return context[o.type](o.name, function(context) {
+              var p;
+              return ((function() {
+                var _i, _len, _ref, _results;
+                _ref = o.content;
+                _results = [];
+                for (_i = 0, _len = _ref.length; _i < _len; _i++) {
+                  p = _ref[_i];
+                  _results.push(cmd(p)(context));
+                }
+                return _results;
+              })()).join("");
+            });
+          };
+      }
+    };
+    return ((function() {
+      var _i, _len, _ref, _results;
+      _ref = ast.content;
+      _results = [];
+      for (_i = 0, _len = _ref.length; _i < _len; _i++) {
+        o = _ref[_i];
+        _results.push(cmd(o)(context));
+      }
+      return _results;
+    })()).join("");
+  };
+
+}).call(this);

lib/tumble.js

@@ -0,0 +1,20 @@
+// Generated by CoffeeScript 1.6.1
+(function() {
+  var engine, lexer, parse;
+
+  lexer = require('./lexer');
+
+  parse = require('./parser');
+
+  engine = require('./engine');
+
+  module.exports = {
+    tumble: lexer.parse,
+    parse: parse,
+    render: function(str, data) {
+      return parse(lexer.parse(str), data);
+    },
+    engine: engine
+  };
+
+}).call(this);

package.json

@@ -1,7 +1,7 @@
 {
-    "name": "Tumble",
-    "description": "Trivial reimplementation of Tumbler template parser",
-    "version": "0.1.0",
+    "name": "tumble",
+    "description": "Trivial reimplementation of Tumbler template parser/renderer",
+    "version": "0.1.2",
     "author": {
         "name": "Kenneth \"Elf\" M. Sternberg",
         "email": "elf.sternberg@gmail.com",
@@ -9,11 +9,12 @@
     },
     "repository": {
         "type": "git",
-        "url": "ssh://elfstenberg@elfsternberg.com/home/elfsternberg/repos/tumble.git"
+        "url": "https://github.com/elfsternberg/tumble.git"
     },
     "licenses": [
         {
-            "type": "PRIVATE"
+            "type": "MIT",
+            "url": "https://raw.github.com/elfsternberg/tumble/master/LICENSE"
         }
     ],
     "main": "lib/tumble",
@@ -27,9 +28,10 @@
         "underscore": "1.4.x"
     },
     "devDependencies": {
+        "coffeescript": "1.6.x",
         "pegjs": "0.7.x",
         "mocha": "1.8.x",
         "chai": "1.5.x"
     },
-    "keywords": []
+    "keywords": ["template", "tumblr"]
 }

src/engine.coffee

@@ -0,0 +1,20 @@
+tumble = require('./lexer').parse;
+parse = require('./parser');
+fs     = require 'fs'
+
+render = (str, options, callback) ->
+    try
+        callback(null, parse(tumble(str), options))
+    catch err
+        callback(err, null)
+
+fromFile = (path, options, callback) ->
+    fs.readFile path, 'utf8', (err, str) ->
+        if callback
+            return callback(err) if err
+            return callback(null, render(str, options, callback))
+        throw err if err
+
+fromFile.render = render
+
+module.exports = fromFile

src/lexer.peg

@@ -1,4 +1,18 @@
 // -*- mode: javascript -*-
+{
+    var _VALID_BLOCK_TYPES = ['if', 'when', 'template', 'many', 'block'];
+    var _VBT_LENGTH = _VALID_BLOCK_TYPES.length;
+
+    function is_valid_block_type(b) {
+        for(var i = 0; i < _VBT_LENGTH; i++) {
+            if (_VALID_BLOCK_TYPES[i] == b) {
+                return true;
+            }
+        }
+        return false;
+    }
+}
+
 
 document
     = ps:part* 
@@ -9,8 +23,14 @@ part
 
 tag_start "tag_start"
     =  ld b:tagname ":" n:tagname rd
+    &{ return is_valid_block_type(b); }
     { return {type: b, name: n }; }
 
+block
+    = t:tag_start ps:part* n:tag_end
+      &{ return (t.type == n.type) && (t.name == n.name) } 
+      { return {unit: 'block', type:t.type, name:t.name, content: ps } }
+
 tag_end
     =  ld '/' b:tagname ":" n:tagname rd 
     { return {type: b, name: n }; }

src/parser.coffee

@@ -1,5 +1,4 @@
 _ = require 'underscore'
-util = require 'util'
 
 class Contexter
 
@@ -39,12 +38,18 @@ class Contexter
         @depth--
         r
 
-    if: (name, cb) ->
-        # Execute and return this specifiecd block if and only if the
+    when: (name, cb) ->
+        # Execute and return this specified block if and only if the
         # requested context is valid.
         p = @has_any_one(name)
         if p then cb(@) else ''
 
+    if: (name, cb) ->
+        # Execute and return this specifiecd block if and only if the
+        # requested context is valid AND current
+        p = @has(name)
+        if p then cb(@) else ''
+
     block: (name, cb) ->
         # Execute and return this specified block if and only if the
         # requested context is valid and entrant.
@@ -56,8 +61,7 @@ class Contexter
         # the specified context if and only if the requested context
         # is valid and is iterable.
         ps = @has(name)
-        if not (ps and _.isArray(ps))
-            return ""
+        return "" unless (ps and _.isArray(ps))
         (_.map ps, (p) => @once(p, cb)).join('')
 
     template: (name, cb) ->
@@ -66,8 +70,16 @@ class Contexter
         return ""
 
     render: (name) ->
-        if @templates[name]? and _.isFunction(@templates[name]) then @templates[name](@) else ""
+        if @templates[name]? and _.isFunction(@templates[name])
+            @depth++
+            throw new Error('recursion-error') if @depth > 10
+            ret = @templates[name](@)
+            @depth--
+            ret
+        else
+            ""
 
+# This is really the compiler at this point...
 
 module.exports = (ast, data) ->
     context = new Contexter(data)

src/tumble.coffee

@@ -0,0 +1,10 @@
+lexer = require './lexer'
+parse = require './parser'
+engine = require './engine'
+
+module.exports = {
+    tumble: lexer.parse,
+    parse: parse,
+    render: (str, data) -> parse(lexer.parse(str), data)
+    engine: engine
+}

test/01_basics_mocha.coffee

@@ -6,7 +6,7 @@ util   = require 'util'
 fs     = require 'fs'
 path   = require 'path'
 
-tumble = require('../lib/tumble').parse;
+tumble = require('../lib/lexer').parse;
 parse = require('../lib/parser');
 
 test_data = JSON.parse(fs.readFileSync(path.join(__dirname, 'data.json'), 'utf-8'))