changeLicense.py: support new license style

Add support for the new licenses (that are commented out linewise via
//) to changeLicense.py that until know just knew about the old-style
licenses commented as /*block*/.

Change-Id: If29c4a49e210cf7516ae93fb1b7ef7e9f5a51f34
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

src/libs/qmljs/parser/changeLicense.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python3
 import sys
 import os
 
@@ -6,19 +6,47 @@ if not len(sys.argv) >= 3:
    print("Usage: %s license files..." % os.path.basename(sys.argv[0]))
    sys.exit()
 
+def detectLicense(fileContent: list[str]) -> tuple[int, int]:
+    for i, line in enumerate(fileContent):
+        if fileContent[i].startswith('//'):
+            """
+            new license style (commented with //): return first noncomment-line
+            after commented license
+            """
+            for j, line in enumerate(fileContent[i:]):
+                if not line.startswith('//'):
+                    return (i, i + j)
+            return (i, len(fileContent))
+
+        if fileContent[i].startswith('/*'):
+            """
+            old license style (commented as /*block*/): return line after the
+            block-comment
+            """
+            for j, line in enumerate(fileContent[i:]):
+                if line.endswith('*/\n'):
+                    return (i, i + j + 1)
+            raise ValueError("Encountered EOF while in the license comment")
+        # else case: probably the generated codes "#line ..."
+
+    raise ValueError("Encountered EOF without finding any license")
+
+
 licenseFileName = sys.argv[1]
 licenseText = ""
 with open(licenseFileName, 'r') as f:
-    licenseText = f.read()
-    licenseText = licenseText[0:licenseText.find('*/')]
+    licenseText = f.read().splitlines(keepends=True)
+    start, stop = detectLicense(licenseText)
+    licenseText = licenseText[start:stop]
 
 files = sys.argv[2:]
 for fileName in files:
     with open(fileName, 'r') as f:
-        text = f.read()
-    oldEnd = text.find('*/')
-    if oldEnd == -1:
-        oldEnd = 0
-    text = licenseText + text[oldEnd:]
+        text = f.read().splitlines(keepends=True)
+    start, stop = detectLicense(text)
+    if stop == -1:
+        stop = 0
     with open(fileName, 'w') as f:
-        f.write(text)
+        f.writelines(text[0:start])
+        f.writelines(licenseText)
+        f.writelines(text[stop:])