| ... | ... | @@ -850,20 +850,56 @@ pub fn indexOfAnyPos(comptime T: type, slice: []const T, start_index: usize, val |
| 850 | 850 | pub fn indexOf(comptime T: type, haystack: []const T, needle: []const T) ?usize { |
| 851 | 851 | return indexOfPos(T, haystack, 0, needle); |
| 852 | 852 | } |
| 853 | |
| 854 | /// Find the index in a slice of a sub-slice, searching from the end backwards. |
| 855 | /// To start looking at a different index, slice the haystack first. |
| 856 | fn lastIndexOfNaive(comptime T: type, haystack: []const T, needle: []const T) ?usize { |
| 857 | if (needle.len > haystack.len) return null; |
| 858 | |
| 859 | var i: usize = haystack.len - needle.len; |
| 860 | while (true) : (i -= 1) { |
| 861 | if (mem.eql(T, haystack[i .. i + needle.len], needle)) return i; |
| 862 | if (i == 0) return null; |
| 863 | } |
| 864 | } |
| 865 | |
| 866 | fn indexOfPosNaive(comptime T: type, haystack: []const T, start_index: usize, needle: []const T) ?usize { |
| 867 | if (needle.len > haystack.len) return null; |
| 868 | |
| 869 | var i: usize = start_index; |
| 870 | const end = haystack.len - needle.len; |
| 871 | while (i <= end) : (i += 1) { |
| 872 | if (eql(T, haystack[i .. i + needle.len], needle)) return i; |
| 873 | } |
| 874 | return null; |
| 875 | } |
| 876 | |
| 877 | fn boyerMooreHorspoolPreprocess(pattern: []const u8, table: []usize) void { |
| 878 | for (table) |*c| { |
| 879 | c.* = pattern.len; |
| 880 | } |
| 881 | |
| 882 | var i: usize = 0; |
| 883 | while (i < pattern.len - 1) : (i += 1) { |
| 884 | table[pattern[i]] = pattern.len - 1 - i; |
| 885 | } |
| 886 | } |
| 853 | 887 | /// Find the index in a slice of a sub-slice, searching from the end backwards. |
| 854 | 888 | /// To start looking at a different index, slice the haystack first. |
| 855 | 889 | // Reverse boyer-moore-horspool algorithm |
| 856 | 890 | pub fn lastIndexOf(comptime T: type, haystack: []const T, needle: []const T) ?usize { |
| 891 | if (T != u8 or haystack.len < 32 or needle.len <= 2) |
| 892 | return lastIndexOfNaive(T, haystack, needle); |
| 893 | |
| 857 | 894 | if (needle.len > haystack.len or needle.len == 0) return null; |
| 895 | var table: [256]usize = undefined; |
| 896 | boyerMooreHorspoolPreprocess(needle, table[0..]); |
| 858 | 897 | |
| 859 | | var i: usize = needle.len - 1; |
| 860 | | while (i < haystack.len) { |
| 861 | | const reverseIndex = haystack.len - i - 1; |
| 862 | | if (indexOfScalar(T, needle, haystack[reverseIndex])) |index| { |
| 863 | | const haystackIndex = reverseIndex - index; |
| 864 | | if (haystackIndex + needle.len <= haystack.len and mem.eql(T, haystack[haystackIndex .. haystackIndex + needle.len], needle)) return haystackIndex; |
| 865 | | } |
| 866 | | i += needle.len; |
| 898 | var i: usize = 0; |
| 899 | while (i <= haystack.len - needle.len) { |
| 900 | const reverseIndex = haystack.len - i - needle.len - 1; |
| 901 | if (mem.eql(T, haystack[reverseIndex .. reverseIndex + needle.len], needle)) return i; |
| 902 | i += table[haystack[reverseIndex + needle.len - 1]]; |
| 867 | 903 | } |
| 868 | 904 | |
| 869 | 905 | return null; |
| ... | ... | @@ -871,15 +907,17 @@ pub fn lastIndexOf(comptime T: type, haystack: []const T, needle: []const T) ?us |
| 871 | 907 | |
| 872 | 908 | // Boyer-moore-horspool algorithm |
| 873 | 909 | pub fn indexOfPos(comptime T: type, haystack: []const T, start_index: usize, needle: []const T) ?usize { |
| 910 | if (T != u8 or haystack.len < 32 or needle.len <= 2) |
| 911 | return indexOfPosNaive(T, haystack, start_index, needle); |
| 912 | |
| 874 | 913 | if (needle.len > haystack.len or needle.len == 0) return null; |
| 914 | var table: [256]usize = undefined; |
| 915 | boyerMooreHorspoolPreprocess(needle, table[0..]); |
| 875 | 916 | |
| 876 | | var i: usize = start_index + needle.len - 1; |
| 877 | | while (i < haystack.len) { |
| 878 | | if (lastIndexOfScalar(T, needle, haystack[i])) |index| { |
| 879 | | const haystackIndex = i - index; |
| 880 | | if (haystackIndex + needle.len <= haystack.len and mem.eql(T, haystack[haystackIndex .. haystackIndex + needle.len], needle)) return haystackIndex; |
| 881 | | } |
| 882 | | i += needle.len; |
| 917 | var i: usize = start_index; |
| 918 | while (i <= haystack.len - needle.len) { |
| 919 | if (mem.eql(T, haystack[i .. i + needle.len], needle)) return i; |
| 920 | i += table[haystack[i + needle.len - 1]]; |
| 883 | 921 | } |
| 884 | 922 | |
| 885 | 923 | return null; |
dec05eba <dec05eba@protonmail.com> 2020-09-05 11:24:05+02:00
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