Improved JSON string parsing

include/wx/private/json.h

@@ -14,74 +14,72 @@ namespace wxJSON
 {
 
 // Decode a string literal including escape sequences
-// If the input is not quoted string it will be returned as the input
+// Returns false if the input string is not a valid JSON string
-wxString DecodeString(const wxString& str)
+bool DecodeString(const wxString& in, wxString* out)
 {
-    if (!str.starts_with('"') || !str.ends_with('"'))
+    const wxWCharBuffer buf = in.wc_str();
-        return str;
+    const wchar_t* ch = buf.data();
-
+    // String has to chart with a quote
-    wxString result;
+    if (*(ch++) != '"')
-    const wxWCharBuffer buf = str.wc_str();
+        return false;
+    out->reserve(buf.length());
     const wchar_t* end = buf.data() + buf.length() - 1;
-    for (const wchar_t* ch = buf.data() + 1; ch < end; ++ch)
+    for (; ch < end; ++ch)
     {
         if (*ch == '\\')
         {
             switch (*(++ch))
             {
             case 'b':
-                result.append('\b');
+                out->append('\b');
                 break;
             case 'n':
-                result.append('\n');
+                out->append('\n');
                 break;
             case 'r':
-                result.append('\r');
+                out->append('\r');
                 break;
             case 't':
-                result.append('\t');
+                out->append('\t');
                 break;
-            case 'v':
+            case 'f':
-                result.append('\v');
+                out->append('\f');
                 break;
-            case '\'':
+            case '/':
-                result.append('\'');
+                out->append('/');
                 break;
             case '"':
-                result.append('"');
+                out->append('"');
                 break;
             case '\\':
-                result.append('\\');
+                out->append('\\');
                 break;
             case 'u':
+#if SIZEOF_WCHAR_T == 2
+                            // In this case, we handle surrogates without doing anything special was wchar_t strings use UTF-17 encoding.
                 if (wxIsxdigit(ch[1]) && wxIsxdigit(ch[2]) &&
                     wxIsxdigit(ch[3]) && wxIsxdigit(ch[4]))
                 {
-                    wxUChar uchar = wxHexToDec(wxString(&ch[3], 2)) |
+                    wchar_t uchar = wxHexToDec(wxString(&ch[3], 2)) |
                         wxHexToDec(wxString(&ch[1], 2)) >> 8;
-                    result.append(uchar);
+                    out->append(uchar);
                     ch += 4;
                 }
+#else
+    #error Implement correct surrogate handling.
+#endif
                 break;
-            case 'x':
-                if (wxIsxdigit(ch[1]) && wxIsxdigit(ch[2]))
-                {
-                    wxChar hchar = wxHexToDec(wxString(&ch[1], 2));
-                    result.append(hchar);
-                    ch += 2;
-                }
-                break;
-
             default:
-                result.append(*ch);
+                return false;
                 break;
             }
         }
         else
-            result.append(*ch);
+            out->append(*ch);
     }
 
-    return result;
+    // String has to end with a quote
+    return (*ch) == '"';
 }
 
 } // namespace JSON

src/msw/webview_edge.cpp

@@ -811,7 +811,10 @@ bool wxWebViewEdge::RunScript(const wxString& javascript, wxString* output)
         if (RunScriptSync(wrapJS.GetUnwrappedOutputCode() + ";", &result))
         {
             if (output)
-                *output = wxJSON::DecodeString(result);
+                // Try to decode JSON string or return original
+                // result if it's not a valid JSON string
+                if (!wxJSON::DecodeString(result, output))
+                    *output = result;
             result.clear();
         }