1 files changed, 14 insertions, 2 deletions
diff --git a/tabulate.cpp b/tabulate.cpp
index f5cfb4f..7b262da 100644
--- a/tabulate.cpp
+++ b/tabulate.cpp
@@ -26,7 +26,7 @@ static void usage(const char *argv0) {
     "has multiple values in the input, the values are appended using the separator\n"
     "character.\n"
     "Row, column and table labels are printed in order of occurrence in the input.\n"
-    "UTF-8 is assumed for string-length calculation.\n"
+    "String-length calculation assumes UTF-8 and ignores ANSI escape sequences.\n"
     "\n"
     "Options:\n"
     "  -h        Show help.\n"
@@ -96,8 +96,20 @@ static std::ostream& operator<<(std::ostream &os, Spaces spaces) {
 }
 
 static int swidth(const std::string &s) {
+  bool saw_escape = false;
+  bool in_ansi_escape = false;
   int len = 0;
-  for (char c : s) len += (c & 0xc0) != 0x80;
+  for (char c : s) {
+    if (in_ansi_escape) {
+      if (0x40 <= c && c <= 0x7E) in_ansi_escape = false;
+    } else if (c == '\x1B') {
+      saw_escape = true;
+    } else if (saw_escape && c == '[') {
+      in_ansi_escape = true;
+    } else {
+      len += (c & 0xc0) != 0x80;
+    }
+  }
   return len;
 }