From f61f7c131fc896af23437880778556e506e73018 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Ekl=C3=B6f?= <daniel@ekloef.se>
Date: Mon, 1 Feb 2021 09:55:18 +0100
Subject: [PATCH] url-mode: auto-detect: heuristics for parenthesis and
 brackets
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While parenthesis and brackets _are_ valid URL characters, there are
many times when we do *not* want them to be part of the URL.

For example, in markdown we write “[text](url)”, or even
“[![alt-text](url-1)](url-2)”.

Here, the URLs are clearly *not* “url)” or “url-1)](url2)”.
---
 url-mode.c | 47 ++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 40 insertions(+), 7 deletions(-)

diff --git a/url-mode.c b/url-mode.c
index a4fea23f..fecbaa6b 100644
--- a/url-mode.c
+++ b/url-mode.c
@@ -147,6 +147,9 @@ auto_detected(struct terminal *term)
     wchar_t url[term->cols * term->rows + 1];
     size_t len = 0;
 
+    ssize_t parenthesis = 0;
+    ssize_t brackets = 0;
+
     for (int r = 0; r < term->rows; r++) {
         const struct row *row = grid_row_in_view(term->grid, r);
 
@@ -182,6 +185,8 @@ auto_detected(struct terminal *term)
 
                         wcsncpy(url, proto, prot_len);
                         len = prot_len;
+
+                        parenthesis = brackets = 0;
                         break;
                     }
                 }
@@ -193,18 +198,47 @@ auto_detected(struct terminal *term)
                 // static const wchar_t unwise[] = L"{}|\\^[]`";
                 // static const wchar_t reserved[] = L";/?:@&=+$,";
 
+                bool emit_url = false;
                 switch (wc) {
                 case L'a'...L'z':
                 case L'0'...L'9':
                 case L'-': case L'.': case L'_': case L'~': case L':':
-                case L'/': case L'?': case L'#': case L'[': case L']':
-                case L'@': case L'!': case L'$': case L'&': case L'\'':
-                case L'(': case L')': case L'*': case L'+': case L',':
-                case L';': case L'=': case L'"':
+                case L'/': case L'?': case L'#': case L'@': case L'!':
+                case L'$': case L'&': case L'\'': case L'*': case L'+':
+                case L',': case L';': case L'=': case L'"':
                     url[len++] = wc;
                     break;
 
-                default: {
+                case L'(':
+                    parenthesis++;
+                    url[len++] = wc;
+                    break;
+
+                case L'[':
+                    brackets++;
+                    url[len++] = wc;
+                    break;
+
+                case L')':
+                    if (--parenthesis < 0)
+                        emit_url = true;
+                    else
+                        url[len++] = wc;
+                    break;
+
+                case L']':
+                    if (--brackets < 0)
+                        emit_url = true;
+                    else
+                        url[len++] = wc;
+                    break;
+
+                default:
+                    emit_url = true;
+                    break;
+                }
+
+                if (emit_url) {
                     /* Heuristic to remove trailing characters that
                      * are valid URL characters, but typically not at
                      * the end of the URL */
@@ -241,8 +275,7 @@ auto_detected(struct terminal *term)
 
                     state = STATE_PROTOCOL;
                     len = 0;
-                    break;
-                }
+                    parenthesis = brackets = 0;
                 }
                 break;
             }