1 files changed, 104 insertions, 0 deletions
diff --git a/markdown_it/rules_block/fence.py b/markdown_it/rules_block/fence.py
new file mode 100644
index 0000000..c4f5275
--- /dev/null
+++ b/markdown_it/rules_block/fence.py
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+# fences (``` lang, ~~~ lang)
+import logging
+
+from .state_block import StateBlock
+
+LOGGER = logging.getLogger(__name__)
+
+
+def fence(state: StateBlock, startLine: int, endLine: int, silent: bool):
+
+    LOGGER.debug("entering fence: %s, %s, %s, %s", state, startLine, endLine, silent)
+
+    haveEndMarker = False
+    pos = state.bMarks[startLine] + state.tShift[startLine]
+    maximum = state.eMarks[startLine]
+
+    # if it's indented more than 3 spaces, it should be a code block
+    if state.sCount[startLine] - state.blkIndent >= 4:
+        return False
+
+    if pos + 3 > maximum:
+        return False
+
+    marker = state.srcCharCode[pos]
+
+    # /* ~ */  /* ` */
+    if marker != 0x7E and marker != 0x60:
+        return False
+
+    # scan marker length
+    mem = pos
+    pos = state.skipChars(pos, marker)
+
+    length = pos - mem
+
+    if length < 3:
+        return False
+
+    markup = state.src[mem:pos]
+    params = state.src[pos:maximum]
+
+    # /* ` */
+    if marker == 0x60:
+        if chr(marker) in params:
+            return False
+
+    # Since start is found, we can report success here in validation mode
+    if silent:
+        return True
+
+    # search end of block
+    nextLine = startLine
+
+    while True:
+        nextLine += 1
+        if nextLine >= endLine:
+            # unclosed block should be autoclosed by end of document.
+            # also block seems to be autoclosed by end of parent
+            break
+
+        pos = mem = state.bMarks[nextLine] + state.tShift[nextLine]
+        maximum = state.eMarks[nextLine]
+
+        if pos < maximum and state.sCount[nextLine] < state.blkIndent:
+            # non-empty line with negative indent should stop the list:
+            # - ```
+            #  test
+            break
+
+        if state.srcCharCode[pos] != marker:
+            continue
+
+        if state.sCount[nextLine] - state.blkIndent >= 4:
+            # closing fence should be indented less than 4 spaces
+            continue
+
+        pos = state.skipChars(pos, marker)
+
+        # closing code fence must be at least as long as the opening one
+        if pos - mem < length:
+            continue
+
+        # make sure tail has spaces only
+        pos = state.skipSpaces(pos)
+
+        if pos < maximum:
+            continue
+
+        haveEndMarker = True
+        # found!
+        break
+
+    # If a fence has heading spaces, they should be removed from its inner block
+    length = state.sCount[startLine]
+
+    state.line = nextLine + (1 if haveEndMarker else 0)
+
+    token = state.push("fence", "code", 0)
+    token.info = params
+    token.content = state.getLines(startLine + 1, nextLine, length, True)
+    token.markup = markup
+    token.map = [startLine, state.line]
+
+    return True