Implement collecting

3 files changed, 19 insertions, 0 deletions

diff --git a/src/dice.js b/src/dice.js
index 0197f25..1e15937 100644
--- a/src/dice.js
+++ b/src/dice.js
@@ -222,6 +222,10 @@ const repeat = (die1, die2) => {
   }
 }
 
+const collect = die => {
+  return () => [() => roll(die)]
+}
+
 exports.pool = pool
 exports.roll = roll
 exports.constant = constant
@@ -244,3 +248,4 @@ exports.againUnder = againUnder
 exports.thresholdHigh = thresholdHigh
 exports.thresholdLow = thresholdLow
 exports.repeat = repeat
+exports.collect = collect
diff --git a/src/lexer.js b/src/lexer.js
index 6b75129..88bd188 100644
--- a/src/lexer.js
+++ b/src/lexer.js
@@ -26,6 +26,8 @@ newLexemeType('times', '\\*')
 newLexemeType('divide', '/')
 newLexemeType('(', '\\(')
 newLexemeType(')', '\\)')
+newLexemeType('[', '\\[')
+newLexemeType(']', '\\]')
 newLexemeType('E', 'E')
 newLexemeType('e', 'e')
 newLexemeType('K', 'K')
diff --git a/src/parser.js b/src/parser.js
index acae9ad..3cf6d55 100644
--- a/src/parser.js
+++ b/src/parser.js
@@ -44,6 +44,16 @@ newSymbol('constant', function() {
   return { type: 'constant', value: this.value }
 })
 
+const newBrackets = (openSymbol, closeSymbol, valueWrapper) => {
+  newSymbol(openSymbol, function(parser) {
+    const value = parser.expression(1)
+    parser.match(closeSymbol)
+    return valueWrapper(value)
+  })
+
+  newSymbol(closeSymbol)
+}
+
 newSymbol('(', function(parser) {
   const value = parser.expression(1)
   parser.match(')')
@@ -52,6 +62,8 @@ newSymbol('(', function(parser) {
 
 newSymbol(')')
 
+newBrackets('[', ']', value => ({ type: 'collect', value: value }))
+
 newDieOperation('d')
 newSymbol('d', (parser) => {
   return {