Merge pull request #7123 from n8sh/issue-20098

Fix Issue 20098 - Improve result of printing std.regex compiled pattern merged-on-behalf-of: Nicholas Wilson <thewilsonator@users.noreply.github.com>
dlang · Aug 4, 2019 · cc9a56f · cc9a56f
2 parents 5094f68 + e226022
commit cc9a56f
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diff --git a/std/regex/internal/ir.d b/std/regex/internal/ir.d
@@ -72,6 +72,20 @@ enum RegexOption: uint {
 //do not reorder this list
 alias RegexOptionNames = AliasSeq!('g', 'i', 'x', 'U', 'm', 's');
 static assert( RegexOption.max < 0x80);
+
+package(std) string regexOptionsToString()(uint flags) nothrow pure @safe
+{
+    flags &= (RegexOption.max << 1) - 1;
+    if (!flags)
+        return "";
+    char[RegexOptionNames.length] buffer = void;
+    size_t pos = 0;
+    foreach (i, flag; __traits(allMembers, RegexOption))
+        if (flags & __traits(getMember, RegexOption, flag))
+            buffer[pos++] = RegexOptionNames[i];
+    return buffer[0 .. pos].idup;
+}
+
 // flags that allow guide execution of engine
 enum RegexInfo : uint { oneShot = 0x80 }
 
@@ -709,6 +723,20 @@ package(std.regex):
         writeln("Max counter nesting depth: ", maxCounterDepth);
     }
 
+    public string toString()() const
+    {
+        import std.format : format;
+        static if (is(typeof(pattern) : string))
+            alias patternString = pattern;
+        else
+        {
+            import std.conv : to;
+            auto patternString = conv.to!string(pattern);
+        }
+        auto quotedEscapedPattern = format("%(%s %)", [patternString]);
+        auto flagString = regexOptionsToString(flags);
+        return "Regex!" ~ Char.stringof ~ "(" ~ quotedEscapedPattern ~ ", \"" ~ flagString ~ "\")";
+    }
 }
 
 // The stuff below this point is temporarrily part of IR module

diff --git a/std/regex/package.d b/std/regex/package.d
@@ -413,6 +413,18 @@ if (isSomeString!(S))
     assert(m.front[1] == "12");
 }
 
+@system unittest
+{
+    import std.conv : to;
+    import std.string : indexOf;
+
+    immutable pattern = "s+";
+    auto regexString = to!string(regex(pattern, "U"));
+    assert(regexString.length <= pattern.length + 100, "String representation shouldn't be unreasonably bloated.");
+    assert(indexOf(regexString, "s+") >= 0, "String representation should include pattern.");
+    assert(indexOf(regexString, 'U') >= 0, "String representation should include flags.");
+}
+
 public auto regexImpl(S)(S pattern, const(char)[] flags="")
 if (isSomeString!(S))
 {