1 files changed, 102 insertions, 0 deletions
diff --git a/markdown_it/rules_inline/emphasis.py b/markdown_it/rules_inline/emphasis.py
new file mode 100644
index 0000000..9001b09
--- /dev/null
+++ b/markdown_it/rules_inline/emphasis.py
@@ -0,0 +1,102 @@
+# Process *this* and _that_
+#
+
+from .state_inline import Delimiter, StateInline
+
+
+def tokenize(state: StateInline, silent: bool):
+    """Insert each marker as a separate text token, and add it to delimiter list"""
+    start = state.pos
+    marker = state.srcCharCode[start]
+
+    if silent:
+        return False
+
+    # /* _ */  /* * */
+    if marker != 0x5F and marker != 0x2A:
+        return False
+
+    scanned = state.scanDelims(state.pos, marker == 0x2A)
+
+    for i in range(scanned.length):
+        token = state.push("text", "", 0)
+        token.content = chr(marker)
+        state.delimiters.append(
+            Delimiter(
+                marker=marker,
+                length=scanned.length,
+                jump=i,
+                token=len(state.tokens) - 1,
+                end=-1,
+                open=scanned.can_open,
+                close=scanned.can_close,
+            )
+        )
+
+    state.pos += scanned.length
+
+    return True
+
+
+def _postProcess(state, delimiters):
+
+    i = len(delimiters) - 1
+    while i >= 0:
+        startDelim = delimiters[i]
+
+        # /* _ */  /* * */
+        if startDelim.marker != 0x5F and startDelim.marker != 0x2A:
+            i -= 1
+            continue
+
+        # Process only opening markers
+        if startDelim.end == -1:
+            i -= 1
+            continue
+
+        endDelim = delimiters[startDelim.end]
+
+        # If the previous delimiter has the same marker and is adjacent to this one,
+        # merge those into one strong delimiter.
+        #
+        # `<em><em>whatever</em></em>` -> `<strong>whatever</strong>`
+        #
+        isStrong = (
+            i > 0
+            and delimiters[i - 1].end == startDelim.end + 1
+            and delimiters[i - 1].token == startDelim.token - 1
+            and delimiters[startDelim.end + 1].token == endDelim.token + 1
+            and delimiters[i - 1].marker == startDelim.marker
+        )
+
+        ch = chr(startDelim.marker)
+
+        token = state.tokens[startDelim.token]
+        token.type = "strong_open" if isStrong else "em_open"
+        token.tag = "strong" if isStrong else "em"
+        token.nesting = 1
+        token.markup = ch + ch if isStrong else ch
+        token.content = ""
+
+        token = state.tokens[endDelim.token]
+        token.type = "strong_close" if isStrong else "em_close"
+        token.tag = "strong" if isStrong else "em"
+        token.nesting = -1
+        token.markup = ch + ch if isStrong else ch
+        token.content = ""
+
+        if isStrong:
+            state.tokens[delimiters[i - 1].token].content = ""
+            state.tokens[delimiters[startDelim.end + 1].token].content = ""
+            i -= 1
+
+        i -= 1
+
+
+def postProcess(state: StateInline):
+    """Walk through delimiter list and replace text tokens with tags."""
+    _postProcess(state, state.delimiters)
+
+    for token in state.tokens_meta:
+        if token and "delimiters" in token:
+            _postProcess(state, token["delimiters"])