// Written in the D programming language.

/*
 * Placed into the Public Domain.
 */

/****
 * Demangle D mangled names.
 * Macros:
 *        WIKI = Phobos/StdDemangle
 */

/* Authors:
 *        Walter Bright, Digital Mars, www.digitalmars.com
 *        Thomas Kuehne
 *        Frits van Bommel
 */

module std.demangle;

//debug=demangle;                // uncomment to turn on debugging printf's

private import std.ctype;
private import std.string;
import std.conv;
private import std.utf;
import std.contracts;

private import std.stdio;

private class MangleException : Exception
{
    this()
    {
        super("MangleException");
    }
}

/*****************************
 * Demangle D mangled names.
 *
 * If it is not a D mangled name, it returns its argument name.
 * Example:
 *        This program reads standard in and writes it to standard out,
 *        pretty-printing any found D mangled names.
-------------------
import std.stdio;
import std.ctype;
import std.demangle;

int main()
{   char[] buffer;
    bool inword;
    int c;

    while ((c = fgetc(stdin)) != EOF)
    {
        if (inword)
        {
            if (c == '_' || isalnum(c))
                buffer ~= cast(char) c;
            else
            {
                inword = false;
                writef(demangle(buffer), cast(char) c);
            }
        }
        else
        {   if (c == '_' || isalpha(c))
            {        inword = true;
                buffer.length = 0;
                buffer ~= cast(char) c;
            }
            else
                writef(cast(char) c);
        }
    }
    if (inword)
        writef(demangle(buffer));
    return 0;
}
-------------------
 */

string demangle(string name)
{
    size_t ni = 2;
    string delegate() fparseTemplateInstanceName;

    static void error()
    {
        //writefln("error()");
        throw new MangleException();
    }

    static ubyte ascii2hex(char c)
    {
        if (!isxdigit(c))
            error();
        return cast(ubyte)
              ( (c >= 'a') ? c - 'a' + 10 :
                (c >= 'A') ? c - 'A' + 10 :
                             c - '0'
              );
    }

    size_t parseNumber()
    {
        //writefln("parseNumber() %d", ni);
        size_t result;

        while (ni < name.length && isdigit(name[ni]))
        {   int i = name[ni] - '0';
            if (result > (size_t.max - i) / 10)
                error();
            result = result * 10 + i;
            ni++;
        }
        return result;
    }

    string parseSymbolName()
    {
        //writefln("parseSymbolName() %d", ni);
        size_t i = parseNumber();
        if (ni + i > name.length)
            error();
        string result;
        if (i >= 5 &&
            name[ni] == '_' &&
            name[ni + 1] == '_' &&
            name[ni + 2] == 'T')
        {
            size_t nisave = ni;
            bool err;
            ni += 3;
            try
            {
                result = fparseTemplateInstanceName();
                if (ni != nisave + i)
                    err = true;
            }
            catch (MangleException me)
            {
                err = true;
            }
            ni = nisave;
            if (err)
                goto L1;
            goto L2;
        }
      L1:
        result = name[ni .. ni + i];
      L2:
        ni += i;
        return result;
    }

    string parseQualifiedName()
    {
        //writefln("parseQualifiedName() %d", ni);
        string result;

        while (ni < name.length && isdigit(name[ni]))
        {
            if (result.length)
                result ~= ".";
            result ~= parseSymbolName();
        }
        return result;
    }

    string parseType(string identifier = null)
    {
        //writefln("parseType() %d", ni);
        int isdelegate = 0;
        bool hasthisptr = false; /// For function/delegate types: expects a 'this' pointer as last argument
      Lagain:
        if (ni >= name.length)
            error();
        string p;
        switch (name[ni++])
        {
            case 'v':        p = "void";        goto L1;
            case 'b':        p = "bool";        goto L1;
            case 'g':        p = "byte";        goto L1;
            case 'h':        p = "ubyte";        goto L1;
            case 's':        p = "short";        goto L1;
            case 't':        p = "ushort";        goto L1;
            case 'i':        p = "int";        goto L1;
            case 'k':        p = "uint";        goto L1;
            case 'l':        p = "long";        goto L1;
            case 'm':        p = "ulong";        goto L1;
            case 'f':        p = "float";        goto L1;
            case 'd':        p = "double";        goto L1;
            case 'e':        p = "real";        goto L1;
            case 'o':        p = "ifloat";        goto L1;
            case 'p':        p = "idouble";        goto L1;
            case 'j':        p = "ireal";        goto L1;
            case 'q':        p = "cfloat";        goto L1;
            case 'r':        p = "cdouble";        goto L1;
            case 'c':        p = "creal";        goto L1;
            case 'a':        p = "char";        goto L1;
            case 'u':        p = "wchar";        goto L1;
            case 'w':        p = "dchar";        goto L1;

            case 'A':                                // dynamic array
                p = parseType() ~ "[]";
                goto L1;

            case 'P':                                // pointer
                p = parseType() ~ "*";
                goto L1;

            case 'G':                                // static array
            {        size_t ns = ni;
                parseNumber();
                size_t ne = ni;
                p = parseType() ~ "[" ~ name[ns .. ne] ~ "]";
                goto L1;
            }

            case 'H':                                // associative array
                p = parseType();
                p = parseType() ~ "[" ~ p ~ "]";
                goto L1;

            case 'D':                                // delegate
                isdelegate = 1;
                goto Lagain;

            case 'M':
                hasthisptr = true;
                goto Lagain;

            case 'y':
                p = "immutable(" ~ parseType() ~ ")";
                goto L1;

            case 'x':
                p = "const(" ~ parseType() ~ ")";
                goto L1;

            case 'O':
                p = "shared(" ~ parseType() ~ ")";
                goto L1;

            case 'F':                                // D function
            case 'U':                                // C function
            case 'W':                                // Windows function
            case 'V':                                // Pascal function
            case 'R':                                // C++ function
            {        char mc = name[ni - 1];
                string args;

                while (1)
                {
                    if (ni >= name.length)
                        error();
                    char c = name[ni];
                    if (c == 'Z')
                        break;
                    if (c == 'X')
                    {
                        if (!args.length) error();
                        args ~= " ...";
                        break;
                    }
                    if (args.length)
                        args ~= ", ";
                    switch (c)
                    {
                        case 'J':
                            args ~= "out ";
                            ni++;
                            goto default;

                        case 'K':
                            args ~= "inout ";
                            ni++;
                            goto default;

                        case 'L':
                            args ~= "lazy ";
                            ni++;
                            goto default;

                        default:
                            args ~= parseType();
                            continue;

                        case 'Y':
                            args ~= "...";
                            break;
                    }
                    break;
                }
                ni++;
                if (!isdelegate && identifier.length)
                {
                    switch (mc)
                    {
                        case 'F': p = null;                break; // D function
                        case 'U': p = "extern (C) ";       break; // C function
                        case 'W': p = "extern (Windows) "; break; // Windows function
                        case 'V': p = "extern (Pascal) ";  break; // Pascal function
                        default:  assert(0);
                    }
                    p ~= parseType() ~ " " ~ identifier ~ "(" ~ args ~ ")";
                    return p;
                }
                p = parseType() ~
                    (isdelegate ? " delegate(" : " function(") ~
                    args ~ ")";
                isdelegate = 0;
                goto L1;
            }

            case 'C':        p = "class ";        goto L2;
            case 'S':        p = "struct ";        goto L2;
            case 'E':        p = "enum ";        goto L2;
            case 'T':        p = "typedef ";        goto L2;

            L2:        p ~= parseQualifiedName();
                goto L1;

            L1:
                if (isdelegate)
                    error();                // 'D' must be followed by function
                if (identifier.length)
                    p ~= " " ~ identifier;
                return p;

            default:
                size_t i = ni - 1;
                ni = name.length;
                p = name[i .. length];
                goto L1;
        }
    }

    string parseTemplateInstanceName()
    {
        auto result = parseSymbolName() ~ "!(";
        int nargs;

        while (1)
        {   size_t i;

            if (ni >= name.length)
                error();
            if (nargs && name[ni] != 'Z')
                result ~= ", ";
            nargs++;
            switch (name[ni++])
            {
                case 'T':
                    result ~= parseType();
                    continue;

                case 'V':

                    void getReal()
                    {   real r;
                        ubyte *p = cast(ubyte *)&r;

                        if (ni + 10 * 2 > name.length)
                            error();
                        for (i = 0; i < 10; i++)
                        {   ubyte b;

                            b = cast(ubyte)
                                (
                                 (ascii2hex(name[ni + i * 2]) << 4) +
                                  ascii2hex(name[ni + i * 2 + 1])
                                );
                            p[i] = b;
                        }
                        result ~= format(r);
                        ni += 10 * 2;
                    }

                    result ~= parseType() ~ " ";
                    if (ni >= name.length)
                        error();
                    switch (name[ni++])
                    {
                    case '0': .. case '9':
                            i = ni - 1;
                            while (ni < name.length && isdigit(name[ni]))
                                ni++;
                            result ~= name[i .. ni];
                            break;

                        case 'N':
                            i = ni;
                            while (ni < name.length && isdigit(name[ni]))
                                ni++;
                            if (i == ni)
                                error();
                            result ~= "-" ~ name[i .. ni];
                            break;

                        case 'n':
                            result ~= "null";
                            break;

                        case 'e':
                            getReal();
                            break;

                        case 'c':
                            getReal();
                            result ~= '+';
                            getReal();
                            result ~= 'i';
                            break;

                        case 'a':
                        case 'w':
                        case 'd':
                        {   char m = name[ni - 1];
                            if (m == 'a')
                                m = 'c';
                            size_t n = parseNumber();
                            if (ni >= name.length || name[ni++] != '_' ||
                                ni + n * 2 > name.length)
                                error();
                            result ~= '"';
                            for (i = 0; i < n; i++)
                            {
                                auto c = cast(char)
                                    ((ascii2hex(name[ni + i * 2]) << 4) +
                                            ascii2hex(name[ni + i * 2 + 1]));
                                result ~= cast(char)c;
                            }
                            ni += n * 2;
                            result ~= '"';
                            result ~= m;
                            break;
                        }

                        default:
                            error();
                            break;
                    }
                    continue;

                case 'S':
                    result ~= parseSymbolName();
                    continue;

                case 'Z':
                    break;

                default:
                    error();
            }
            break;
        }
        result ~= ")";
        return assumeUnique(result);
    }

    if (name.length < 3 ||
        name[0] != '_' ||
        name[1] != 'D' ||
        !isdigit(name[2]))
    {
        goto Lnot;
    }

    fparseTemplateInstanceName = &parseTemplateInstanceName;

    try
    {
        auto result = parseQualifiedName();
        result = parseType(result);
        while(ni < name.length){
                result ~= " . " ~ parseType(parseQualifiedName());
        }

        if (ni != name.length)
            goto Lnot;
        return result;
    }
    catch (MangleException e)
    {
    }

Lnot:
    // Not a recognized D mangled name; so return original
    return name;
}


unittest
{
    debug(demangle) printf("demangle.demangle.unittest\n");

    static string[2][] table =
    [
        [ "printf",        "printf" ],
        [ "_foo",        "_foo" ],
        [ "_D88",        "_D88" ],
        [ "_D4test3fooAa", "char[] test.foo"],
        [ "_D8demangle8demangleFAaZAa", "char[] demangle.demangle(char[])" ],
        [ "_D6object6Object8opEqualsFC6ObjectZi", "int object.Object.opEquals(class Object)" ],
        [ "_D4test2dgDFiYd", "double delegate(int, ...) test.dg" ],
        [ "_D4test58__T9factorialVde67666666666666860140VG5aa5_68656c6c6fVPvnZ9factorialf", "float test.factorial!(double 4.2, char[5] \"hello\"c, void* null).factorial" ],
        [ "_D4test101__T9factorialVde67666666666666860140Vrc9a999999999999d9014000000000000000c00040VG5aa5_68656c6c6fVPvnZ9factorialf", "float test.factorial!(double 4.2, cdouble 6.8+3i, char[5] \"hello\"c, void* null).factorial" ],
        [ "_D4test34__T3barVG3uw3_616263VG3wd3_646566Z1xi", "int test.bar!(wchar[3] \"abc\"w, dchar[3] \"def\"d).x" ],
        [ "_D8demangle4testFLC6ObjectLDFLiZiZi", "int demangle.test(lazy class Object, lazy int delegate(lazy int))"],
        [ "_D8demangle4testFAiXi", "int demangle.test(int[] ...)"],
        [ "_D8demangle4testFLAiXi", "int demangle.test(lazy int[] ...)"],
        [ "_D6plugin8generateFiiZAya", "immutable(char)[] plugin.generate(int, int)"],
        [ "_D6plugin8generateFiiZAxa", "const(char)[] plugin.generate(int, int)"],
        [ "_D6plugin8generateFiiZAOa", "shared(char)[] plugin.generate(int, int)"]
    ];

    foreach (i, name; table)
    {
        string r = demangle(name[0]);
        assert(r == name[1],
                "table entry #" ~ to!string(i) ~ ": '" ~ name[0]
                ~ "' demangles as '" ~ r ~ "' but is expected to be '"
                ~ name[1] ~ "'");

    }
}




