From b2aee1a9789c74e5eba16ac71d6a7b256fc61067 Mon Sep 17 00:00:00 2001
From: Alex Kocharin <alex@kocharin.ru>
Date: Wed, 22 Jul 2015 16:09:25 +0300
Subject: [PATCH] Expand tabs only when it's needed, as per CommonMark 0.21

---
 lib/common/utils.js                           | 10 +++
 lib/parser_block.js                           |  2 +-
 lib/rules_block/blockquote.js                 | 65 ++++++++++++---
 lib/rules_block/code.js                       |  4 +-
 lib/rules_block/fence.js                      |  6 +-
 lib/rules_block/heading.js                    |  6 +-
 lib/rules_block/hr.js                         |  6 +-
 lib/rules_block/html_block.js                 |  2 +-
 lib/rules_block/lheading.js                   |  4 +-
 lib/rules_block/list.js                       | 62 +++++++++++---
 lib/rules_block/paragraph.js                  |  4 +-
 lib/rules_block/reference.js                  | 21 +++--
 lib/rules_block/state_block.js                | 70 +++++++++++-----
 lib/rules_block/table.js                      |  4 +-
 lib/rules_core/normalize.js                   | 21 +----
 lib/rules_inline/escape.js                    |  8 +-
 lib/rules_inline/image.js                     |  9 +-
 lib/rules_inline/link.js                      |  9 +-
 test/fixtures/commonmark/bad.txt              | 83 -------------------
 test/fixtures/commonmark/good.txt             | 52 ++++++++++++
 .../markdown-it/commonmark_extras.txt         | 27 ++++++
 21 files changed, 298 insertions(+), 177 deletions(-)

diff --git a/lib/common/utils.js b/lib/common/utils.js
index 34ac689..9a8bcee 100644
--- a/lib/common/utils.js
+++ b/lib/common/utils.js
@@ -151,6 +151,15 @@ function escapeRE (str) {
 
 ////////////////////////////////////////////////////////////////////////////////
 
+function isSpace(code) {
+  switch (code) {
+    case 0x09:
+    case 0x20:
+      return true;
+  }
+  return false;
+}
+
 // Zs (unicode class) || [\t\f\v\r\n]
 function isWhiteSpace(code) {
   if (code >= 0x2000 && code <= 0x200A) { return true; }
@@ -258,6 +267,7 @@ exports.fromCodePoint       = fromCodePoint;
 // exports.replaceEntities     = replaceEntities;
 exports.escapeHtml          = escapeHtml;
 exports.arrayReplaceAt      = arrayReplaceAt;
+exports.isSpace             = isSpace;
 exports.isWhiteSpace        = isWhiteSpace;
 exports.isMdAsciiPunct      = isMdAsciiPunct;
 exports.isPunctChar         = isPunctChar;
diff --git a/lib/parser_block.js b/lib/parser_block.js
index 921c851..84f1e2b 100644
--- a/lib/parser_block.js
+++ b/lib/parser_block.js
@@ -59,7 +59,7 @@ ParserBlock.prototype.tokenize = function (state, startLine, endLine) {
 
     // Termination condition for nested calls.
     // Nested calls currently used for blockquotes & lists
-    if (state.tShift[line] < state.blkIndent) { break; }
+    if (state.sCount[line] < state.blkIndent) { break; }
 
     // If nesting level exceeded - skip tail to the end. That's not ordinary
     // situation and we should not care about content.
diff --git a/lib/rules_block/blockquote.js b/lib/rules_block/blockquote.js
index 0e5a43b..30c3702 100644
--- a/lib/rules_block/blockquote.js
+++ b/lib/rules_block/blockquote.js
@@ -2,9 +2,11 @@
 
 'use strict';
 
+var isSpace = require('../common/utils').isSpace;
+
 
 module.exports = function blockquote(state, startLine, endLine, silent) {
-  var nextLine, lastLineEmpty, oldTShift, oldBMarks, oldIndent, oldParentType, lines,
+  var nextLine, lastLineEmpty, oldTShift, oldSCount, oldBMarks, oldIndent, oldParentType, lines, initial, offset, ch,
       terminatorRules, token,
       i, l, terminate,
       pos = state.bMarks[startLine] + state.tShift[startLine],
@@ -17,19 +19,39 @@ module.exports = function blockquote(state, startLine, endLine, silent) {
   // so no point trying to find the end of it in silent mode
   if (silent) { return true; }
 
-  // skip one optional space after '>'
+  // skip one optional space (but not tab, check cmark impl) after '>'
   if (state.src.charCodeAt(pos) === 0x20) { pos++; }
 
   oldIndent = state.blkIndent;
   state.blkIndent = 0;
 
+  // skip spaces after ">" and re-calculate offset
+  initial = offset = state.sCount[startLine] + pos - (state.bMarks[startLine] + state.tShift[startLine]);
+
   oldBMarks = [ state.bMarks[startLine] ];
   state.bMarks[startLine] = pos;
 
-  // check if we have an empty blockquote
-  pos = pos < max ? state.skipSpaces(pos) : pos;
+  while (pos < max) {
+    ch = state.src.charCodeAt(pos);
+
+    if (isSpace(ch)) {
+      if (ch === 0x09) {
+        offset += 4 - offset % 4;
+      } else {
+        offset++;
+      }
+    } else {
+      break;
+    }
+
+    pos++;
+  }
+
   lastLineEmpty = pos >= max;
 
+  oldSCount = [ state.sCount[startLine] ];
+  state.sCount[startLine] = offset - initial;
+
   oldTShift = [ state.tShift[startLine] ];
   state.tShift[startLine] = pos - state.bMarks[startLine];
 
@@ -54,7 +76,7 @@ module.exports = function blockquote(state, startLine, endLine, silent) {
   //      - - -
   //     ```
   for (nextLine = startLine + 1; nextLine < endLine; nextLine++) {
-    if (state.tShift[nextLine] < oldIndent) { break; }
+    if (state.sCount[nextLine] < oldIndent) { break; }
 
     pos = state.bMarks[nextLine] + state.tShift[nextLine];
     max = state.eMarks[nextLine];
@@ -67,15 +89,36 @@ module.exports = function blockquote(state, startLine, endLine, silent) {
     if (state.src.charCodeAt(pos++) === 0x3E/* > */) {
       // This line is inside the blockquote.
 
-      // skip one optional space after '>'
+      // skip one optional space (but not tab, check cmark impl) after '>'
       if (state.src.charCodeAt(pos) === 0x20) { pos++; }
 
+      // skip spaces after ">" and re-calculate offset
+      initial = offset = state.sCount[nextLine] + pos - (state.bMarks[nextLine] + state.tShift[nextLine]);
+
       oldBMarks.push(state.bMarks[nextLine]);
       state.bMarks[nextLine] = pos;
 
-      pos = pos < max ? state.skipSpaces(pos) : pos;
+      while (pos < max) {
+        ch = state.src.charCodeAt(pos);
+
+        if (isSpace(ch)) {
+          if (ch === 0x09) {
+            offset += 4 - offset % 4;
+          } else {
+            offset++;
+          }
+        } else {
+          break;
+        }
+
+        pos++;
+      }
+
       lastLineEmpty = pos >= max;
 
+      oldSCount.push(state.sCount[nextLine]);
+      state.sCount[nextLine] = offset - initial;
+
       oldTShift.push(state.tShift[nextLine]);
       state.tShift[nextLine] = pos - state.bMarks[nextLine];
       continue;
@@ -96,12 +139,11 @@ module.exports = function blockquote(state, startLine, endLine, silent) {
 
     oldBMarks.push(state.bMarks[nextLine]);
     oldTShift.push(state.tShift[nextLine]);
+    oldSCount.push(state.sCount[nextLine]);
 
-    // A negative number means that this is a paragraph continuation;
+    // A negative indentation means that this is a paragraph continuation
     //
-    // Any negative number will do the job here, but it's better for it
-    // to be large enough to make any bugs obvious.
-    state.tShift[nextLine] = -1;
+    state.sCount[nextLine] = -1;
   }
 
   oldParentType = state.parentType;
@@ -124,6 +166,7 @@ module.exports = function blockquote(state, startLine, endLine, silent) {
   for (i = 0; i < oldTShift.length; i++) {
     state.bMarks[i + startLine] = oldBMarks[i];
     state.tShift[i + startLine] = oldTShift[i];
+    state.sCount[i + startLine] = oldSCount[i];
   }
   state.blkIndent = oldIndent;
 
diff --git a/lib/rules_block/code.js b/lib/rules_block/code.js
index dcf3336..74bc42a 100644
--- a/lib/rules_block/code.js
+++ b/lib/rules_block/code.js
@@ -6,7 +6,7 @@
 module.exports = function code(state, startLine, endLine/*, silent*/) {
   var nextLine, last, token;
 
-  if (state.tShift[startLine] - state.blkIndent < 4) { return false; }
+  if (state.sCount[startLine] - state.blkIndent < 4) { return false; }
 
   last = nextLine = startLine + 1;
 
@@ -15,7 +15,7 @@ module.exports = function code(state, startLine, endLine/*, silent*/) {
       nextLine++;
       continue;
     }
-    if (state.tShift[nextLine] - state.blkIndent >= 4) {
+    if (state.sCount[nextLine] - state.blkIndent >= 4) {
       nextLine++;
       last = nextLine;
       continue;
diff --git a/lib/rules_block/fence.js b/lib/rules_block/fence.js
index cf72e78..a02bd5f 100644
--- a/lib/rules_block/fence.js
+++ b/lib/rules_block/fence.js
@@ -47,7 +47,7 @@ module.exports = function fence(state, startLine, endLine, silent) {
     pos = mem = state.bMarks[nextLine] + state.tShift[nextLine];
     max = state.eMarks[nextLine];
 
-    if (pos < max && state.tShift[nextLine] < state.blkIndent) {
+    if (pos < max && state.sCount[nextLine] < state.blkIndent) {
       // non-empty line with negative indent should stop the list:
       // - ```
       //  test
@@ -56,7 +56,7 @@ module.exports = function fence(state, startLine, endLine, silent) {
 
     if (state.src.charCodeAt(pos) !== marker) { continue; }
 
-    if (state.tShift[nextLine] - state.blkIndent >= 4) {
+    if (state.sCount[nextLine] - state.blkIndent >= 4) {
       // closing fence should be indented less than 4 spaces
       continue;
     }
@@ -77,7 +77,7 @@ module.exports = function fence(state, startLine, endLine, silent) {
   }
 
   // If a fence has heading spaces, they should be removed from its inner block
-  len = state.tShift[startLine];
+  len = state.sCount[startLine];
 
   state.line = nextLine + (haveEndMarker ? 1 : 0);
 
diff --git a/lib/rules_block/heading.js b/lib/rules_block/heading.js
index 1cf4723..9b8eee4 100644
--- a/lib/rules_block/heading.js
+++ b/lib/rules_block/heading.js
@@ -2,6 +2,8 @@
 
 'use strict';
 
+var isSpace = require('../common/utils').isSpace;
+
 
 module.exports = function heading(state, startLine, endLine, silent) {
   var ch, level, tmp, token,
@@ -26,9 +28,9 @@ module.exports = function heading(state, startLine, endLine, silent) {
 
   // Let's cut tails like '    ###  ' from the end of string
 
-  max = state.skipCharsBack(max, 0x20, pos); // space
+  max = state.skipSpacesBack(max, pos);
   tmp = state.skipCharsBack(max, 0x23, pos); // #
-  if (tmp > pos && state.src.charCodeAt(tmp - 1) === 0x20/* space */) {
+  if (tmp > pos && isSpace(state.src.charCodeAt(tmp - 1))) {
     max = tmp;
   }
 
diff --git a/lib/rules_block/hr.js b/lib/rules_block/hr.js
index 0abaf66..8638f04 100644
--- a/lib/rules_block/hr.js
+++ b/lib/rules_block/hr.js
@@ -2,6 +2,8 @@
 
 'use strict';
 
+var isSpace = require('../common/utils').isSpace;
+
 
 module.exports = function hr(state, startLine, endLine, silent) {
   var marker, cnt, ch, token,
@@ -17,12 +19,12 @@ module.exports = function hr(state, startLine, endLine, silent) {
     return false;
   }
 
-  // markers can be mixed with spaces, but there should be at least 3 one
+  // markers can be mixed with spaces, but there should be at least 3 of them
 
   cnt = 1;
   while (pos < max) {
     ch = state.src.charCodeAt(pos++);
-    if (ch !== marker && ch !== 0x20/* space */) { return false; }
+    if (ch !== marker && !isSpace(ch)) { return false; }
     if (ch === marker) { cnt++; }
   }
 
diff --git a/lib/rules_block/html_block.js b/lib/rules_block/html_block.js
index 0d9426b..abef36d 100644
--- a/lib/rules_block/html_block.js
+++ b/lib/rules_block/html_block.js
@@ -48,7 +48,7 @@ module.exports = function html_block(state, startLine, endLine, silent) {
   // Let's roll down till block end.
   if (!HTML_SEQUENCES[i][1].test(lineText)) {
     for (; nextLine < endLine; nextLine++) {
-      if (state.tShift[nextLine] < state.blkIndent) { break; }
+      if (state.sCount[nextLine] < state.blkIndent) { break; }
 
       pos = state.bMarks[nextLine] + state.tShift[nextLine];
       max = state.eMarks[nextLine];
diff --git a/lib/rules_block/lheading.js b/lib/rules_block/lheading.js
index 8668fd0..76343bf 100644
--- a/lib/rules_block/lheading.js
+++ b/lib/rules_block/lheading.js
@@ -8,11 +8,11 @@ module.exports = function lheading(state, startLine, endLine/*, silent*/) {
       next = startLine + 1;
 
   if (next >= endLine) { return false; }
-  if (state.tShift[next] < state.blkIndent) { return false; }
+  if (state.sCount[next] < state.blkIndent) { return false; }
 
   // Scan next line
 
-  if (state.tShift[next] - state.blkIndent > 3) { return false; }
+  if (state.sCount[next] - state.blkIndent > 3) { return false; }
 
   pos = state.bMarks[next] + state.tShift[next];
   max = state.eMarks[next];
diff --git a/lib/rules_block/list.js b/lib/rules_block/list.js
index 49b9a5b..bb28e6b 100644
--- a/lib/rules_block/list.js
+++ b/lib/rules_block/list.js
@@ -2,11 +2,13 @@
 
 'use strict';
 
+var isSpace = require('../common/utils').isSpace;
+
 
 // Search `[-+*][\n ]`, returns next pos arter marker on success
 // or -1 on fail.
 function skipBulletListMarker(state, startLine) {
-  var marker, pos, max;
+  var marker, pos, max, ch;
 
   pos = state.bMarks[startLine] + state.tShift[startLine];
   max = state.eMarks[startLine];
@@ -19,9 +21,13 @@ function skipBulletListMarker(state, startLine) {
     return -1;
   }
 
-  if (pos < max && state.src.charCodeAt(pos) !== 0x20) {
-    // " 1.test " - is not a list item
-    return -1;
+  if (pos < max) {
+    ch = state.src.charCodeAt(pos);
+
+    if (!isSpace(ch)) {
+      // " -test " - is not a list item
+      return -1;
+    }
   }
 
   return pos;
@@ -66,9 +72,13 @@ function skipOrderedListMarker(state, startLine) {
   }
 
 
-  if (pos < max && state.src.charCodeAt(pos) !== 0x20/* space */) {
-    // " 1.test " - is not a list item
-    return -1;
+  if (pos < max) {
+    ch = state.src.charCodeAt(pos);
+
+    if (!isSpace(ch)) {
+      // " 1.test " - is not a list item
+      return -1;
+    }
   }
   return pos;
 }
@@ -89,13 +99,18 @@ function markTightParagraphs(state, idx) {
 
 module.exports = function list(state, startLine, endLine, silent) {
   var nextLine,
+      initial,
+      offset,
       indent,
       oldTShift,
       oldIndent,
+      oldLIndent,
       oldTight,
       oldParentType,
       start,
       posAfterMarker,
+      ch,
+      pos,
       max,
       indentAfterMarker,
       markerValue,
@@ -154,14 +169,34 @@ module.exports = function list(state, startLine, endLine, silent) {
   terminatorRules = state.md.block.ruler.getRules('list');
 
   while (nextLine < endLine) {
-    contentStart = state.skipSpaces(posAfterMarker);
+    pos = posAfterMarker;
     max = state.eMarks[nextLine];
 
+    initial = offset = state.sCount[nextLine] + posAfterMarker - (state.bMarks[startLine] + state.tShift[startLine]);
+
+    while (pos < max) {
+      ch = state.src.charCodeAt(pos);
+
+      if (isSpace(ch)) {
+        if (ch === 0x09) {
+          offset += 4 - offset % 4;
+        } else {
+          offset++;
+        }
+      } else {
+        break;
+      }
+
+      pos++;
+    }
+
+    contentStart = pos;
+
     if (contentStart >= max) {
       // trimming space in "-    \n  3" case, indent is 1 here
       indentAfterMarker = 1;
     } else {
-      indentAfterMarker = contentStart - posAfterMarker;
+      indentAfterMarker = offset - initial;
     }
 
     // If we have more than 4 spaces, the indent is 1
@@ -170,7 +205,7 @@ module.exports = function list(state, startLine, endLine, silent) {
 
     // "  -  test"
     //  ^^^^^ - calculating total length of this thing
-    indent = (posAfterMarker - state.bMarks[nextLine]) + indentAfterMarker;
+    indent = initial + indentAfterMarker;
 
     // Run subparser & write tokens
     token        = state.push('list_item_open', 'li', 1);
@@ -180,11 +215,13 @@ module.exports = function list(state, startLine, endLine, silent) {
     oldIndent = state.blkIndent;
     oldTight = state.tight;
     oldTShift = state.tShift[startLine];
+    oldLIndent = state.sCount[startLine];
     oldParentType = state.parentType;
-    state.tShift[startLine] = contentStart - state.bMarks[startLine];
     state.blkIndent = indent;
     state.tight = true;
     state.parentType = 'list';
+    state.tShift[startLine] = contentStart - state.bMarks[startLine];
+    state.sCount[startLine] = offset;
 
     state.md.block.tokenize(state, startLine, endLine, true);
 
@@ -198,6 +235,7 @@ module.exports = function list(state, startLine, endLine, silent) {
 
     state.blkIndent = oldIndent;
     state.tShift[startLine] = oldTShift;
+    state.sCount[startLine] = oldLIndent;
     state.tight = oldTight;
     state.parentType = oldParentType;
 
@@ -217,7 +255,7 @@ module.exports = function list(state, startLine, endLine, silent) {
     //
     // Try to check if list is terminated or continued.
     //
-    if (state.tShift[nextLine] < state.blkIndent) { break; }
+    if (state.sCount[nextLine] < state.blkIndent) { break; }
 
     // fail if terminating block found
     terminate = false;
diff --git a/lib/rules_block/paragraph.js b/lib/rules_block/paragraph.js
index d9dca25..18a860d 100644
--- a/lib/rules_block/paragraph.js
+++ b/lib/rules_block/paragraph.js
@@ -13,10 +13,10 @@ module.exports = function paragraph(state, startLine/*, endLine*/) {
   for (; nextLine < endLine && !state.isEmpty(nextLine); nextLine++) {
     // this would be a code block normally, but after paragraph
     // it's considered a lazy continuation regardless of what's there
-    if (state.tShift[nextLine] - state.blkIndent > 3) { continue; }
+    if (state.sCount[nextLine] - state.blkIndent > 3) { continue; }
 
     // quirk for blockquotes, this line should already be checked by that rule
-    if (state.tShift[nextLine] < 0) { continue; }
+    if (state.sCount[nextLine] < 0) { continue; }
 
     // Some tags can terminate paragraph without empty line.
     terminate = false;
diff --git a/lib/rules_block/reference.js b/lib/rules_block/reference.js
index 260726b..23f662b 100644
--- a/lib/rules_block/reference.js
+++ b/lib/rules_block/reference.js
@@ -4,6 +4,7 @@
 var parseLinkDestination = require('../helpers/parse_link_destination');
 var parseLinkTitle       = require('../helpers/parse_link_title');
 var normalizeReference   = require('../common/utils').normalizeReference;
+var isSpace              = require('../common/utils').isSpace;
 
 
 module.exports = function reference(state, startLine, _endLine, silent) {
@@ -48,10 +49,10 @@ module.exports = function reference(state, startLine, _endLine, silent) {
   for (; nextLine < endLine && !state.isEmpty(nextLine); nextLine++) {
     // this would be a code block normally, but after paragraph
     // it's considered a lazy continuation regardless of what's there
-    if (state.tShift[nextLine] - state.blkIndent > 3) { continue; }
+    if (state.sCount[nextLine] - state.blkIndent > 3) { continue; }
 
     // quirk for blockquotes, this line should already be checked by that rule
-    if (state.tShift[nextLine] < 0) { continue; }
+    if (state.sCount[nextLine] < 0) { continue; }
 
     // Some tags can terminate paragraph without empty line.
     terminate = false;
@@ -92,7 +93,7 @@ module.exports = function reference(state, startLine, _endLine, silent) {
     ch = str.charCodeAt(pos);
     if (ch === 0x0A) {
       lines++;
-    } else if (ch === 0x20) {
+    } else if (isSpace(ch)) {
       /*eslint no-empty:0*/
     } else {
       break;
@@ -121,7 +122,7 @@ module.exports = function reference(state, startLine, _endLine, silent) {
     ch = str.charCodeAt(pos);
     if (ch === 0x0A) {
       lines++;
-    } else if (ch === 0x20) {
+    } else if (isSpace(ch)) {
       /*eslint no-empty:0*/
     } else {
       break;
@@ -142,7 +143,11 @@ module.exports = function reference(state, startLine, _endLine, silent) {
   }
 
   // skip trailing spaces until the rest of the line
-  while (pos < max && str.charCodeAt(pos) === 0x20/* space */) { pos++; }
+  while (pos < max) {
+    ch = str.charCodeAt(pos);
+    if (!isSpace(ch)) { break; }
+    pos++;
+  }
 
   if (pos < max && str.charCodeAt(pos) !== 0x0A) {
     if (title) {
@@ -151,7 +156,11 @@ module.exports = function reference(state, startLine, _endLine, silent) {
       title = '';
       pos = destEndPos;
       lines = destEndLineNo;
-      while (pos < max && str.charCodeAt(pos) === 0x20/* space */) { pos++; }
+      while (pos < max) {
+        ch = str.charCodeAt(pos);
+        if (!isSpace(ch)) { break; }
+        pos++;
+      }
     }
   }
 
diff --git a/lib/rules_block/state_block.js b/lib/rules_block/state_block.js
index 7f608b3..f08bdb2 100644
--- a/lib/rules_block/state_block.js
+++ b/lib/rules_block/state_block.js
@@ -3,10 +3,11 @@
 'use strict';
 
 var Token = require('../token');
+var isSpace = require('../common/utils').isSpace;
 
 
 function StateBlock(src, md, env, tokens) {
-  var ch, s, start, pos, len, indent, indent_found;
+  var ch, s, start, pos, len, indent, offset, indent_found;
 
   this.src = src;
 
@@ -23,7 +24,8 @@ function StateBlock(src, md, env, tokens) {
 
   this.bMarks = [];  // line begin offsets for fast jumps
   this.eMarks = [];  // line end offsets for fast jumps
-  this.tShift = [];  // indent for each line
+  this.tShift = [];  // offsets of the first non-space characters (tabs not expanded)
+  this.sCount = [];  // indents for each line (tabs expanded)
 
   // block parser variables
   this.blkIndent  = 0; // required block content indent
@@ -42,15 +44,20 @@ function StateBlock(src, md, env, tokens) {
   // Create caches
   // Generate markers.
   s = this.src;
-  indent = 0;
   indent_found = false;
 
-  for (start = pos = indent = 0, len = s.length; pos < len; pos++) {
+  for (start = pos = indent = offset = 0, len = s.length; pos < len; pos++) {
     ch = s.charCodeAt(pos);
 
     if (!indent_found) {
-      if (ch === 0x20/* space */) {
+      if (isSpace(ch)) {
         indent++;
+
+        if (ch === 0x09) {
+          offset += 4 - offset % 4;
+        } else {
+          offset++;
+        }
         continue;
       } else {
         indent_found = true;
@@ -62,9 +69,11 @@ function StateBlock(src, md, env, tokens) {
       this.bMarks.push(start);
       this.eMarks.push(pos);
       this.tShift.push(indent);
+      this.sCount.push(offset);
 
       indent_found = false;
       indent = 0;
+      offset = 0;
       start = pos + 1;
     }
   }
@@ -73,6 +82,7 @@ function StateBlock(src, md, env, tokens) {
   this.bMarks.push(s.length);
   this.eMarks.push(s.length);
   this.tShift.push(0);
+  this.sCount.push(0);
 
   this.lineMax = this.bMarks.length - 1; // don't count last fake line
 }
@@ -106,8 +116,21 @@ StateBlock.prototype.skipEmptyLines = function skipEmptyLines(from) {
 
 // Skip spaces from given position.
 StateBlock.prototype.skipSpaces = function skipSpaces(pos) {
+  var ch;
+
   for (var max = this.src.length; pos < max; pos++) {
-    if (this.src.charCodeAt(pos) !== 0x20/* space */) { break; }
+    ch = this.src.charCodeAt(pos);
+    if (!isSpace(ch)) { break; }
+  }
+  return pos;
+};
+
+// Skip spaces from given position in reverse.
+StateBlock.prototype.skipSpacesBack = function skipSpacesBack(pos, min) {
+  if (pos <= min) { return pos; }
+
+  while (pos > min) {
+    if (!isSpace(this.src.charCodeAt(--pos))) { return pos + 1; }
   }
   return pos;
 };
@@ -132,28 +155,18 @@ StateBlock.prototype.skipCharsBack = function skipCharsBack(pos, code, min) {
 
 // cut lines range from source.
 StateBlock.prototype.getLines = function getLines(begin, end, indent, keepLastLF) {
-  var i, first, last, queue, shift,
+  var i, lineIndent, ch, first, last, queue, lineStart,
       line = begin;
 
   if (begin >= end) {
     return '';
   }
 
-  // Opt: don't use push queue for single line;
-  if (line + 1 === end) {
-    first = this.bMarks[line] + Math.min(this.tShift[line], indent);
-    last = this.eMarks[end - 1] + (keepLastLF ? 1 : 0);
-    return this.src.slice(first, last);
-  }
-
   queue = new Array(end - begin);
 
   for (i = 0; line < end; line++, i++) {
-    shift = this.tShift[line];
-    if (shift > indent) { shift = indent; }
-    if (shift < 0) { shift = 0; }
-
-    first = this.bMarks[line] + shift;
+    lineIndent = 0;
+    lineStart = first = this.bMarks[line];
 
     if (line + 1 < end || keepLastLF) {
       // No need for bounds check because we have fake entry on tail.
@@ -162,6 +175,25 @@ StateBlock.prototype.getLines = function getLines(begin, end, indent, keepLastLF
       last = this.eMarks[line];
     }
 
+    while (first < last && lineIndent < indent) {
+      ch = this.src.charCodeAt(first);
+
+      if (isSpace(ch)) {
+        if (ch === 0x09) {
+          lineIndent += 4 - lineIndent % 4;
+        } else {
+          lineIndent++;
+        }
+      } else if (first - lineStart < this.tShift[line]) {
+        // patched tShift masked characters to look like spaces (blockquotes, list markers)
+        lineIndent++;
+      } else {
+        break;
+      }
+
+      first++;
+    }
+
     queue[i] = this.src.slice(first, last);
   }
 
diff --git a/lib/rules_block/table.js b/lib/rules_block/table.js
index 1e1c0e9..c45badb 100644
--- a/lib/rules_block/table.js
+++ b/lib/rules_block/table.js
@@ -62,7 +62,7 @@ module.exports = function table(state, startLine, endLine, silent) {
 
   nextLine = startLine + 1;
 
-  if (state.tShift[nextLine] < state.blkIndent) { return false; }
+  if (state.sCount[nextLine] < state.blkIndent) { return false; }
 
   // first character of the second line should be '|' or '-'
 
@@ -137,7 +137,7 @@ module.exports = function table(state, startLine, endLine, silent) {
   token.map = tbodyLines = [ startLine + 2, 0 ];
 
   for (nextLine = startLine + 2; nextLine < endLine; nextLine++) {
-    if (state.tShift[nextLine] < state.blkIndent) { break; }
+    if (state.sCount[nextLine] < state.blkIndent) { break; }
 
     lineText = getLine(state, nextLine).trim();
     if (lineText.indexOf('|') === -1) { break; }
diff --git a/lib/rules_core/normalize.js b/lib/rules_core/normalize.js
index 4152095..bff5d51 100644
--- a/lib/rules_core/normalize.js
+++ b/lib/rules_core/normalize.js
@@ -3,13 +3,12 @@
 'use strict';
 
 
-var TABS_SCAN_RE = /[\n\t]/g;
 var NEWLINES_RE  = /\r[\n\u0085]|[\u2424\u2028\u0085]/g;
 var NULL_RE      = /\u0000/g;
 
 
 module.exports = function inline(state) {
-  var str, lineStart, lastTabPos;
+  var str;
 
   // Normalize newlines
   str = state.src.replace(NEWLINES_RE, '\n');
@@ -17,23 +16,5 @@ module.exports = function inline(state) {
   // Replace NULL characters
   str = str.replace(NULL_RE, '\uFFFD');
 
-  // Replace tabs with proper number of spaces (1..4)
-  if (str.indexOf('\t') >= 0) {
-    lineStart = 0;
-    lastTabPos = 0;
-
-    str = str.replace(TABS_SCAN_RE, function (match, offset) {
-      var result;
-      if (str.charCodeAt(offset) === 0x0A) {
-        lineStart = offset + 1;
-        lastTabPos = 0;
-        return match;
-      }
-      result = '    '.slice((offset - lineStart - lastTabPos) % 4);
-      lastTabPos = offset - lineStart + 1;
-      return result;
-    });
-  }
-
   state.src = str;
 };
diff --git a/lib/rules_inline/escape.js b/lib/rules_inline/escape.js
index ff32832..e0996e0 100644
--- a/lib/rules_inline/escape.js
+++ b/lib/rules_inline/escape.js
@@ -2,6 +2,8 @@
 
 'use strict';
 
+var isSpace = require('../common/utils').isSpace;
+
 var ESCAPED = [];
 
 for (var i = 0; i < 256; i++) { ESCAPED.push(0); }
@@ -33,7 +35,11 @@ module.exports = function escape(state, silent) {
 
       pos++;
       // skip leading whitespaces from next line
-      while (pos < max && state.src.charCodeAt(pos) === 0x20) { pos++; }
+      while (pos < max) {
+        ch = state.src.charCodeAt(pos);
+        if (!isSpace(ch)) { break; }
+        pos++;
+      }
 
       state.pos = pos;
       return true;
diff --git a/lib/rules_inline/image.js b/lib/rules_inline/image.js
index a5e1630..32355e0 100644
--- a/lib/rules_inline/image.js
+++ b/lib/rules_inline/image.js
@@ -6,6 +6,7 @@ var parseLinkLabel       = require('../helpers/parse_link_label');
 var parseLinkDestination = require('../helpers/parse_link_destination');
 var parseLinkTitle       = require('../helpers/parse_link_title');
 var normalizeReference   = require('../common/utils').normalizeReference;
+var isSpace              = require('../common/utils').isSpace;
 
 
 module.exports = function image(state, silent) {
@@ -45,7 +46,7 @@ module.exports = function image(state, silent) {
     pos++;
     for (; pos < max; pos++) {
       code = state.src.charCodeAt(pos);
-      if (code !== 0x20 && code !== 0x0A) { break; }
+      if (!isSpace(code) && code !== 0x0A) { break; }
     }
     if (pos >= max) { return false; }
 
@@ -67,7 +68,7 @@ module.exports = function image(state, silent) {
     start = pos;
     for (; pos < max; pos++) {
       code = state.src.charCodeAt(pos);
-      if (code !== 0x20 && code !== 0x0A) { break; }
+      if (!isSpace(code) && code !== 0x0A) { break; }
     }
 
     // [link](  <href>  "title"  )
@@ -81,7 +82,7 @@ module.exports = function image(state, silent) {
       //                         ^^ skipping these spaces
       for (; pos < max; pos++) {
         code = state.src.charCodeAt(pos);
-        if (code !== 0x20 && code !== 0x0A) { break; }
+        if (!isSpace(code) && code !== 0x0A) { break; }
       }
     } else {
       title = '';
@@ -102,7 +103,7 @@ module.exports = function image(state, silent) {
     //      ^^ optional whitespace (can include newlines)
     for (; pos < max; pos++) {
       code = state.src.charCodeAt(pos);
-      if (code !== 0x20 && code !== 0x0A) { break; }
+      if (!isSpace(code) && code !== 0x0A) { break; }
     }
 
     if (pos < max && state.src.charCodeAt(pos) === 0x5B/* [ */) {
diff --git a/lib/rules_inline/link.js b/lib/rules_inline/link.js
index 8e9e54e..b4a8808 100644
--- a/lib/rules_inline/link.js
+++ b/lib/rules_inline/link.js
@@ -6,6 +6,7 @@ var parseLinkLabel       = require('../helpers/parse_link_label');
 var parseLinkDestination = require('../helpers/parse_link_destination');
 var parseLinkTitle       = require('../helpers/parse_link_title');
 var normalizeReference   = require('../common/utils').normalizeReference;
+var isSpace              = require('../common/utils').isSpace;
 
 
 module.exports = function link(state, silent) {
@@ -43,7 +44,7 @@ module.exports = function link(state, silent) {
     pos++;
     for (; pos < max; pos++) {
       code = state.src.charCodeAt(pos);
-      if (code !== 0x20 && code !== 0x0A) { break; }
+      if (!isSpace(code) && code !== 0x0A) { break; }
     }
     if (pos >= max) { return false; }
 
@@ -65,7 +66,7 @@ module.exports = function link(state, silent) {
     start = pos;
     for (; pos < max; pos++) {
       code = state.src.charCodeAt(pos);
-      if (code !== 0x20 && code !== 0x0A) { break; }
+      if (!isSpace(code) && code !== 0x0A) { break; }
     }
 
     // [link](  <href>  "title"  )
@@ -79,7 +80,7 @@ module.exports = function link(state, silent) {
       //                         ^^ skipping these spaces
       for (; pos < max; pos++) {
         code = state.src.charCodeAt(pos);
-        if (code !== 0x20 && code !== 0x0A) { break; }
+        if (!isSpace(code) && code !== 0x0A) { break; }
       }
     } else {
       title = '';
@@ -100,7 +101,7 @@ module.exports = function link(state, silent) {
     //      ^^ optional whitespace (can include newlines)
     for (; pos < max; pos++) {
       code = state.src.charCodeAt(pos);
-      if (code !== 0x20 && code !== 0x0A) { break; }
+      if (!isSpace(code) && code !== 0x0A) { break; }
     }
 
     if (pos < max && state.src.charCodeAt(pos) === 0x5B/* [ */) {
diff --git a/test/fixtures/commonmark/bad.txt b/test/fixtures/commonmark/bad.txt
index b5c78a7..9a799f9 100644
--- a/test/fixtures/commonmark/bad.txt
+++ b/test/fixtures/commonmark/bad.txt
@@ -1,86 +1,3 @@
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-src line: 259
-
-.
-	foo	baz		bim
-.
-<pre><code>foo	baz		bim
-</code></pre>
-.
-
-error:
-
-<pre><code>foo baz     bim
-</code></pre>
-
-
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-src line: 266
-
-.
-  	foo	baz		bim
-.
-<pre><code>foo	baz		bim
-</code></pre>
-.
-
-error:
-
-<pre><code>foo baz     bim
-</code></pre>
-
-
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-src line: 273
-
-.
-    a	a
-    ὐ	a
-.
-<pre><code>a	a
-ὐ	a
-</code></pre>
-.
-
-error:
-
-<pre><code>a   a
-ὐ   a
-</code></pre>
-
-
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-src line: 295
-
-.
->	foo	bar
-.
-<blockquote>
-<p>foo	bar</p>
-</blockquote>
-.
-
-error:
-
-<blockquote>
-<p>foo bar</p>
-</blockquote>
-
-
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-src line: 4737
-
-.
-\	\A\a\ \3\φ\«
-.
-<p>\	\A\a\ \3\φ\«</p>
-.
-
-error:
-
-<p>\   \A\a\ \3\φ\«</p>
-
-
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 src line: 6241
 
diff --git a/test/fixtures/commonmark/good.txt b/test/fixtures/commonmark/good.txt
index 296c819..bdb86d3 100644
--- a/test/fixtures/commonmark/good.txt
+++ b/test/fixtures/commonmark/good.txt
@@ -1,3 +1,35 @@
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+src line: 259
+
+.
+	foo	baz		bim
+.
+<pre><code>foo	baz		bim
+</code></pre>
+.
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+src line: 266
+
+.
+  	foo	baz		bim
+.
+<pre><code>foo	baz		bim
+</code></pre>
+.
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+src line: 273
+
+.
+    a	a
+    ὐ	a
+.
+<pre><code>a	a
+ὐ	a
+</code></pre>
+.
+
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 src line: 282
 
@@ -14,6 +46,17 @@ src line: 282
 </ul>
 .
 
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+src line: 295
+
+.
+>	foo	bar
+.
+<blockquote>
+<p>foo	bar</p>
+</blockquote>
+.
+
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 src line: 324
 
@@ -3945,6 +3988,15 @@ src line: 4728
 <p>!&quot;#$%&amp;'()*+,-./:;&lt;=&gt;?@[\]^_`{|}~</p>
 .
 
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+src line: 4737
+
+.
+\	\A\a\ \3\φ\«
+.
+<p>\	\A\a\ \3\φ\«</p>
+.
+
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 src line: 4746
 
diff --git a/test/fixtures/markdown-it/commonmark_extras.txt b/test/fixtures/markdown-it/commonmark_extras.txt
index fe302ae..e6b615b 100644
--- a/test/fixtures/markdown-it/commonmark_extras.txt
+++ b/test/fixtures/markdown-it/commonmark_extras.txt
@@ -245,3 +245,30 @@ test
 <blockquote></blockquote>
 <p><a href="bar">foo</a></p>
 .
+
+Coverage. Tabs in blockquotes.
+.
+   >	 foo
+   > 	 bar
+.
+<blockquote>
+<pre><code> foo
+ bar
+</code></pre>
+</blockquote>
+.
+
+Coverage. Tabs in lists.
+.
+1. 	foo
+
+	     bar
+.
+<ol>
+<li>
+<p>foo</p>
+<pre><code> bar
+</code></pre>
+</li>
+</ol>
+.