nxt.line_column source code

1 /** Conversions from string/file offset to line and column.
2  *
3  * See_Also: https://clang.llvm.org/diagnostics.html
4  */
5 module nxt.line_column;
6 
7 @safe:
8 
9 void diagnoseGNUStyle(Args...)(scope const string tag,
10                                scope const string path,
11                                const LineColumn lc,
12                                Args args)
13 {
14     import std.stdio : writeln;
15     debug writeln(path,
16                   ":", lc.line + 1, // line offset starts at 1
17                   ":", lc.column,   // column counter starts at 0
18                   ": ", tag, ": ", args);
19 }
20 
21 @safe pure nothrow @nogc:
22 
23 struct LineColumn
24 {
25     uint line; ///< 32-bit should suffice for now.
26     uint column; ///< 32-bit should suffice for now.
27 }
28 
29 /** Convert `offset` at `haystack` to line and column. */
30 LineColumn offsetLineColumn(scope const char[] haystack,
31                             size_t offset)
32 {
33     // find 0-based column offset
34     size_t cursor = offset;      // cursor
35     while (cursor != 0) // TODO: extend to support UTF-8
36     {
37         if (cursor >= 1)
38             if (haystack[cursor - 1] == '\n' || // TODO: extend to support UTF-8
39                 haystack[cursor - 1] == '\r')   // TODO: extend to support UTF-8
40                 break;
41         cursor -= 1;
42     }
43     // cursor is not at beginning of line
44 
45     const column = offset - cursor; // column byte offset
46 
47     // find 0-based line offset
48     size_t lineCounter = 0;
49     while (cursor != 0)
50     {
51         if (haystack[cursor - 1] == '\n' ||
52             haystack[cursor - 1] == '\r')
53         {
54             cursor -= 1;
55             if (cursor != 0 &&
56                 (haystack[cursor - 1] == '\r')) // DOS-style line ending "\r\n"
57             {
58                 cursor -= 1;
59             }
60             else            // UNIX-style line ending "\n"
61             {
62             }
63             lineCounter += 1;
64         }
65         else                // no line ending at cursor
66             cursor -= 1;
67     }
68 
69     return typeof(return)(cast(uint)lineCounter,
70                           cast(uint)column);
71 }
72 
73 @safe pure unittest
74 {
75     auto x = "\nx\n y";
76     assert(x.length == 5);
77     assert(x.offsetLineColumn(0) == LineColumn(0, 0));
78     assert(x.offsetLineColumn(1) == LineColumn(1, 0));
79     assert(x.offsetLineColumn(2) == LineColumn(1, 1));
80     assert(x.offsetLineColumn(3) == LineColumn(2, 0));
81     assert(x.offsetLineColumn(4) == LineColumn(2, 1));
82 }
83 
84 version(unittest)
85 {
86     import nxt.dbgio;
87 }