GitHub Issue #9 - support Rule 3 indentation

lib/clojurefmt.js

@@ -60,6 +60,17 @@
     return a.length
   }
 
+  // returns the last item in an Array
+  // returns null if the Array has no items
+  function arrayLast (a) {
+    const s = arraySize(a)
+    if (s === 0) {
+      return null
+    } else {
+      return a[dec(s)]
+    }
+  }
+
   function strConcat (s1, s2) {
     return '' + s1 + s2
   }
@@ -557,6 +568,10 @@
 
   // TODO: some of this information should be calculated when parsing
 
+  function isNonEmptyTextNode (node) {
+    return node && isString(node.text) && node.text !== ''
+  }
+
   function isNewlineNode (n) {
     return n && isString(n.text) && strIncludes(n.text, '\n')
   }
@@ -667,24 +682,31 @@
     if (!wrappingOpener) {
       return 0
     } else {
-      const nextNode = wrappingOpener._nextWithText
+      const nextNodeAfterOpener = wrappingOpener._nextWithText
       const openerTextLength = strLen(wrappingOpener.text)
       const directlyUnderneathOpener = wrappingOpener._colIdx + openerTextLength
 
       if (isReaderConditionalOpener(wrappingOpener)) {
         return directlyUnderneathOpener
         // TODO: pretty sure one or both of these conditions can be removed or combined
-      } else if (nextNode && isParenOpener(nextNode)) {
+      } else if (nextNodeAfterOpener && isParenOpener(nextNodeAfterOpener)) {
         return inc(wrappingOpener._colIdx)
       } else if (isOneSpaceOpener(wrappingOpener)) {
         return inc(wrappingOpener._colIdx)
       } else {
-      // else indent two spaces from the wrapping opener
+        // else indent two spaces from the wrapping opener
         return inc(inc(wrappingOpener._colIdx))
       }
     }
   }
 
+  function numSpacesAfterNewline (newlineNode) {
+    // TODO: make this language neutral
+    const x = newlineNode.text.split('\n')
+    const lastX = arrayLast(x)
+    return strLen(lastX)
+  }
+
   // ---------------------------------------------------------------------------
   // Formatter
 
@@ -703,6 +725,7 @@
     let idx = 0
     let outTxt = ''
     let outputTxtContainsChars = false
+    let lineIdx = 0
 
     // FIXME: need a running paren stack of openers (who are not closed)
     // use this on a newline to determine indentation level
@@ -727,6 +750,12 @@
         const nodeWithExtraInfo = node
         nodeWithExtraInfo._colIdx = colIdx
         nodeWithExtraInfo._nextWithText = nextTextNode
+        nodeWithExtraInfo._parenOpenerLineIdx = lineIdx
+        // an array of tokens on the first line of this parenStack
+        // used to determine if Rule 3 indentation applies
+        nodeWithExtraInfo._openingLineTokens = []
+        nodeWithExtraInfo._rule3Active = false
+        nodeWithExtraInfo._rule3NumSpaces = 0
 
         parenStack.push(nodeWithExtraInfo) // TODO: abstract to language neutral
 
@@ -741,6 +770,17 @@
         parenStack.pop() // TODO: abstract to language neutral
       }
 
+      // add token nodes to the top of the parenStack if we are on the opening line
+      const topOfTheParenStack = stackPeek(parenStack, 0)
+      if (topOfTheParenStack && isTokenNode(node)) {
+        const onOpeningLineOfParenStack = lineIdx === topOfTheParenStack._parenOpenerLineIdx
+        if (onOpeningLineOfParenStack) {
+          node._colIdx = colIdx
+          node._lineIdx = lineIdx
+          topOfTheParenStack._openingLineTokens.push(node)
+        }
+      }
+
       // remove whitespace before a closer (remove-surrounding-whitespace?)
       if (currentNodeIsWhitespace && !isNewlineNode(node) && isParenCloser(nextTextNode)) {
         skipPrintingThisNode = true
@@ -781,15 +821,50 @@
         // if we are not at the end of the nodes array
         if (inc(idx) < numNodes) {
           const topOfTheParenStack = stackPeek(parenStack, 0)
-          const numSpaces = numSpacesForIndentation(topOfTheParenStack)
+          const numSpacesOnNextLine = numSpacesAfterNewline(node)
+
+          // are we inside of a parenStack that crosses into the next line?
+          if (topOfTheParenStack && topOfTheParenStack._parenOpenerLineIdx === lineIdx) {
+            // NOTE: we start this index at 1 in order to skip the first token on the paren opener line
+            // ie: we want to look at tokens 2 or later for Rule 3 alignment
+            let openingLineTokensIdx = 1
+            const numOpeningLineTokens = arraySize(topOfTheParenStack._openingLineTokens)
+            while (openingLineTokensIdx < numOpeningLineTokens) {
+              const openingLineToken = topOfTheParenStack._openingLineTokens[openingLineTokensIdx]
+              if (openingLineToken._colIdx === numSpacesOnNextLine) {
+                // the first token on this line is vertically aligned with a first-line token:
+                // Rule 3 is activated 👍
+                topOfTheParenStack._rule3Active = true
+                topOfTheParenStack._rule3NumSpaces = numSpacesOnNextLine
+
+                // we can exit the loop now
+                openingLineTokensIdx = inc(numOpeningLineTokens)
+              }
+
+              openingLineTokensIdx = inc(openingLineTokensIdx)
+            }
+          }
+
+          let numSpaces = 0
+          if (topOfTheParenStack && topOfTheParenStack._rule3Active) {
+            numSpaces = topOfTheParenStack._rule3NumSpaces
+          } else {
+            numSpaces = numSpacesForIndentation(topOfTheParenStack)
+          }
 
           const indentationStr = repeatString(' ', numSpaces)
           outTxt = strConcat(outTxt, strConcat(newlineStr, indentationStr))
 
           // reset the colIdx
           colIdx = strLen(indentationStr)
+
+          // increment the lineIdx
+          lineIdx = inc(lineIdx)
+          if (isDoubleNewline) {
+            lineIdx = inc(lineIdx)
+          }
         }
-      } else if (isString(node.text) && node.text !== '') {
+      } else if (isNonEmptyTextNode(node)) {
         const isTokenFollowedByOpener = isTokenNode(node) && nextTextNode && isParenOpener(nextTextNode)
         const isParenCloserFollowedByText = isParenCloser(node) && nextTextNode && (isTokenNode(nextTextNode) || isParenOpener(nextTextNode))
         const addSpaceAfterThisNode = isTokenFollowedByOpener || isParenCloserFollowedByText

test/format.test.js

@@ -70,9 +70,9 @@ test('All test_format/ cases should have unique names', () => {
 // only those cases will run
 const onlyRunCertainTests = false
 const certainTests = new Set()
-certainTests.add('Rule 3 Indentation')
+certainTests.add('Rule 3 Indentation 1')
 
-const ignoreSomeTests = true
+const ignoreSomeTests = false
 const ignoreTests = new Set()
 ignoreTests.add('Rule 3 Indentation')
 

test_format/format.eno

@@ -262,7 +262,7 @@
   baz)
 --Expected
 
-# Rule 3 Indentation
+# Rule 3 Indentation 1
 
 --Input
 ;; https://github.com/clj-commons/formatter/issues/9#issuecomment-446167649
@@ -291,3 +291,38 @@
   baz
   qux)
 --Expected
+
+
+# Rule 3 Indentation 2
+
+--Input
+(foo bar
+     baz
+  qux)
+
+(zap bar baz
+         qux
+      wizzle
+                     gee)
+
+(yes tam
+      bif
+     bag
+     hop)
+--Input
+
+--Expected
+(foo bar
+     baz
+     qux)
+
+(zap bar baz
+         qux
+         wizzle
+         gee)
+
+(yes tam
+  bif
+  bag
+  hop)
+--Expected