stringbuilder.pmc

/*
Copyright (C) 2010-2011, Parrot Foundation.

=head1 NAME

src/pmc/stringbuilder.pmc - StringBuilder PMC Class

=head1 DESCRIPTION

TODO: Add description here.

=head2 Methods

=over 4

=cut

*/

#include "parrot/string_funcs.h"

/* HEADERIZER HFILE: none */
/* HEADERIZER BEGIN: static */
/* Don't modify between HEADERIZER BEGIN / HEADERIZER END.  Your changes will be lost. */

PARROT_WARN_UNUSED_RESULT
PARROT_CONST_FUNCTION
static size_t calculate_capacity(PARROT_INTERP, size_t needed);

static void convert_encoding(PARROT_INTERP,
    ARGIN(STR_VTABLE *dest_encoding),
    ARGMOD(STRING *buffer),
    size_t size_to_add)
        __attribute__nonnull__(1)
        __attribute__nonnull__(2)
        __attribute__nonnull__(3)
        FUNC_MODIFIES(*buffer);

#define ASSERT_ARGS_calculate_capacity __attribute__unused__ int _ASSERT_ARGS_CHECK = (0)
#define ASSERT_ARGS_convert_encoding __attribute__unused__ int _ASSERT_ARGS_CHECK = (\
       PARROT_ASSERT_ARG(interp) \
    , PARROT_ASSERT_ARG(dest_encoding) \
    , PARROT_ASSERT_ARG(buffer))
/* Don't modify between HEADERIZER BEGIN / HEADERIZER END.  Your changes will be lost. */
/* HEADERIZER END: static */

#define INITIAL_STRING_CAPACITY 128

pmclass StringBuilder provides string auto_attrs {
    ATTR STRING *buffer;    /* Mutable string to gather results */


/*

=item C<void init()>

Initializes the StringBuilder.

=cut

*/

    VTABLE void init() {
        STATICSELF.init_int(INITIAL_STRING_CAPACITY);
    }


/*

=item C<void init_int()>

Initializes the StringBuilder with initial size of buffer.

=cut

*/

    VTABLE void init_int(INTVAL initial_size) {
        STRING * const buffer = Parrot_gc_new_string_header(INTERP, 0);

        if (initial_size < INITIAL_STRING_CAPACITY)
            initial_size = INITIAL_STRING_CAPACITY;

        Parrot_gc_allocate_string_storage(INTERP, buffer, initial_size);
        buffer->encoding = Parrot_default_encoding_ptr;

        SET_ATTR_buffer(INTERP, SELF, buffer);

        PObj_custom_mark_SET(SELF);
    }


/*

=item C<void init_pmc()>

Initializes the StringBuilder with an array of STRINGs.

=cut

*/

    VTABLE void init_pmc(PMC *ar) {
        const INTVAL count = VTABLE_elements(INTERP, ar);

        if (!count)
            STATICSELF.init_int(INITIAL_STRING_CAPACITY);
        else {
            STRING * const first = VTABLE_get_string_keyed_int(INTERP, ar, 0);
            const INTVAL   size  = Parrot_str_byte_length(INTERP, first);
            INTVAL         i;

            /* it's just an estimate, but estimates help */
            STATICSELF.init_int(size * count);
            SELF.push_string(first);

            for (i = 1; i < count; ++i)
                SELF.push_string(VTABLE_get_string_keyed_int(INTERP, ar, i));
        }
    }

/*

=item C<void mark()>

Mark the buffer.

=cut

*/

    VTABLE void mark() {
        if (PMC_data(SELF)) {
            STRING *buffer;
            GET_ATTR_buffer(INTERP, SELF, buffer);
            Parrot_gc_mark_STRING_alive(INTERP, buffer);
        }
    }

/*

=item C<STRING *get_string()>

Returns created string.

=cut

*/

    VTABLE STRING *get_string() {
        STRING *buffer;
        GET_ATTR_buffer(INTERP, SELF, buffer);
        /* We need to build a new string because outside of StringBuilder
         * strings are immutable. */
        return Parrot_str_clone(INTERP, buffer);
    }

/*

=item C<STRING *push_string()>

Append string to current buffer.

=cut

*/

    VTABLE void push_string(STRING *s) {
        STRING           *buffer;
        size_t            total_size;

        /* Early return on NULL strings */
        if (STRING_IS_NULL(s) || s->strlen == 0)
            return;

        GET_ATTR_buffer(INTERP, SELF, buffer);

        if (buffer->bufused == 0) {
            /* Always copy the encoding of the first string. The IO functions
               assume that the concatenation of utf8 strings doesn't change
               the encoding. */
            buffer->encoding = s->encoding;
        }
        else {
            const STR_VTABLE * const enc =
                  buffer->encoding == s->encoding
                ? buffer->encoding
                : Parrot_str_rep_compatible(interp, buffer, s);

            if (enc) {
                buffer->encoding = enc;
            }
            else {
                /* If strings are incompatible - convert them to utf8 */

                if (s->encoding != Parrot_utf8_encoding_ptr)
                    s = Parrot_utf8_encoding_ptr->to_encoding(interp, s);

                if (buffer->encoding != Parrot_utf8_encoding_ptr)
                    convert_encoding(INTERP, Parrot_utf8_encoding_ptr, buffer, s->bufused);
            }
        }

        total_size = buffer->bufused + s->bufused;

        /* Reallocate if necessary */
        if (total_size > buffer->_buflen) {
            /* Calculate (possibly new) total size */
            total_size = calculate_capacity(INTERP, total_size);

            Parrot_gc_reallocate_string_storage(INTERP, buffer, total_size);
            buffer->_buflen = total_size;
        }

        /* Tack s on the end of buffer */
        memcpy((char *)buffer->_bufstart + buffer->bufused,
                s->strstart, s->bufused);

        /* Update buffer */
        buffer->bufused += s->bufused;
        buffer->strstart = (char *)buffer->_bufstart;
        buffer->strlen  += s->strlen;
        buffer->hashval  = 0; /* hash is invalid */

        PARROT_ASSERT(buffer->bufused <= Buffer_buflen(buffer));
    }

    VTABLE void push_integer(INTVAL value) {
        STRING * s = PARROT_STRINGBUILDER(SELF)->buffer;
        String_iter iter;
        size_t total_size;

        if (s->encoding != Parrot_utf8_encoding_ptr && value > 0x7F) {
            if (s->strlen == 0)
                s->encoding = Parrot_utf8_encoding_ptr;
            else
                convert_encoding(INTERP, Parrot_utf8_encoding_ptr, s, sizeof (INTVAL));
        }

        total_size = s->bufused + sizeof (INTVAL);
        if (total_size > s->_buflen) {
            total_size = calculate_capacity(INTERP, total_size);
            Parrot_gc_reallocate_string_storage(INTERP, s, total_size);
        }

        STRING_ITER_INIT(INTERP, &iter);
        iter.charpos = s->strlen;
        iter.bytepos = s->bufused;
        STRING_iter_set_and_advance(INTERP, s, &iter, value);
        s->strlen = iter.charpos;
        s->bufused = iter.bytepos;
    }

/*

=item C<VTABLE i_concatenate_str()>

=item C<VTABLE i_concatenate()>

Append string. Synonym for push_string

=cut

*/

    VTABLE void i_concatenate_str(STRING *s) {
        STATICSELF.push_string(s);
    }

    VTABLE void i_concatenate(PMC *p) {
        STATICSELF.push_string(VTABLE_get_string(INTERP, p));
    }

    VTABLE void push_pmc(PMC *p) {
        STATICSELF.push_string(VTABLE_get_string(INTERP, p));
    }

/*

=item C<VTABLE set_string_native(STRING)>

=item C<VTABLE set_pmc(PMC)>

Set content of buffer to passed string or PMC

=cut

*/
    VTABLE void set_string_native(STRING *s) {
        STRING * buffer;

        /* Calculate (possibly new) total size */
        const size_t total_size = calculate_capacity(INTERP, s->bufused);

        GET_ATTR_buffer(INTERP, SELF, buffer);

        /* Reallocate if necessary */
        if (total_size > Buffer_buflen(buffer)) {
            Parrot_gc_reallocate_string_storage(INTERP, buffer, total_size);
            buffer->strstart = (char*)buffer->_bufstart;
        }

        /* Tack s on the buffer */
        memcpy((void *)((char*)buffer->_bufstart),
                s->strstart, s->bufused);

        /* Update buffer */
        buffer->bufused  = s->bufused;
        buffer->strlen   = Parrot_str_length(INTERP, s);
        buffer->encoding = s->encoding;
    }

    VTABLE void set_pmc(PMC *s) {
        STATICSELF.set_string_native(VTABLE_get_string(INTERP, s));
    }


/*

=item C<VTABLE get_integer()>

Returns current capacity of allocated buffer.

For testing purpose only?

=cut

*/

    INTVAL get_integer() {
        STRING *buffer;
        GET_ATTR_buffer(INTERP, SELF, buffer);
        return Buffer_buflen(buffer);
    }

/*

=item C<VTABLE substr()>

=cut

*/

    VTABLE STRING *substr(INTVAL offset, INTVAL length) {
        STRING *buffer;
        GET_ATTR_buffer(INTERP, SELF, buffer);
        /* We must clone here because we can reallocate buffer behind the scene... */
        /* TODO Optimize it to avoid creation of redundant STRING */
        return Parrot_str_clone(INTERP,
                STRING_substr(INTERP, buffer, offset, length));
    }

/*

=item C<append_format(string fmt [, pmc args ] [, pmc hash ])>

Add a line to a C<StringBuilder> object according to C<fmt>.
The C<fmt> string can contain any number of "%-replacements"
which are replaced by the corresponding values from C<args>
or C<hash> prior to being appended to the string.  (Here
C<args> is a slurpy array, and C<hash> is a slurpy hash.)

The currently defined replacements include:

    %0 %1 ... %9     the value from the args array at index 0..9
    %,               the values of the args array separated by commas
    %%               a percent sign

A percent-sign followed by any other character that is a hash
key receives the value of the hash element.

=cut

*/

    METHOD append_format(STRING *fmt, PMC *args :slurpy, PMC *hash :slurpy :named) {
        STRING * const percent     = CONST_STRING(INTERP, "%");
        STRING * const comma       = CONST_STRING(INTERP, ",");
        STRING * const comma_space = CONST_STRING(INTERP, ", ");
        PMC    *stringbuilder = SELF;
        INTVAL pos = 0;

        /* Loop over the format string, splitting it into chunks
         * for the string builder. */
        while (pos >= 0) {
            /* Find the next % */
            const INTVAL percentPos = STRING_index(INTERP, fmt, percent, pos);
            STRING *key;

            if (percentPos < 0) {
                if (pos == 0) {
                    VTABLE_push_string(INTERP, stringbuilder, fmt);
                }
                else {
                    /* remaining string can be added as is. */
                    VTABLE_push_string(INTERP, stringbuilder,
                        STRING_substr(INTERP, fmt, pos,
                            Parrot_str_length(INTERP, fmt) -pos));
                    }
                break;
            }
            else {
                /* slurp up to just before the % sign... */
                VTABLE_push_string(INTERP, stringbuilder,
                    STRING_substr(INTERP, fmt, pos, percentPos - pos));
                /* skip the % sign */
                pos = percentPos + 1 ;
            }

            /* key is always a single character */
            key = STRING_substr(INTERP, fmt, pos++, 1);

            if (VTABLE_exists_keyed_str(INTERP, hash, key)) {
                VTABLE_push_string(INTERP, stringbuilder,
                        VTABLE_get_string_keyed_str(INTERP, hash, key));
            }
            else if (Parrot_str_is_cclass(INTERP, enum_cclass_numeric, key, 0)) {
                VTABLE_push_string(INTERP, stringbuilder,
                    VTABLE_get_string_keyed_int(INTERP, args,
                        Parrot_str_to_int(INTERP, key)));
            }
            else if (STRING_equal(INTERP, key, comma)) {
                INTVAL num_args = VTABLE_elements(INTERP, args);
                INTVAL pos_args;

                for (pos_args = 0; pos_args < num_args; ++pos_args) {
                    if (pos_args > 0)
                        VTABLE_push_string(INTERP, stringbuilder, comma_space);
                    VTABLE_push_string(INTERP, stringbuilder,
                        VTABLE_get_string_keyed_int(INTERP, args, pos_args));
                }
            }
            else if (STRING_equal(INTERP, key, percent)) {
                VTABLE_push_string(INTERP, stringbuilder, percent);
            }
            else {
                /* %foo has no special meaning, pass it through unchanged */
                VTABLE_push_string(INTERP, stringbuilder,
                    STRING_substr(INTERP, fmt, pos-2, 2));
            }
        }

        RETURN(PMC *SELF);
    }

/*
=item C<INTVAL get_string_length()>

Returns length of currently built string.

=cut
*/

    METHOD get_string_length() {
        STRING *buffer;
        INTVAL  length;
        GET_ATTR_buffer(INTERP, SELF, buffer);
        length = Parrot_str_length(INTERP, buffer);
        RETURN(INTVAL length);
    }


/*

=back

=cut

*/

}


/*

=head2 Helper functions.

=over 4

=cut

*/

/*

=item C<static size_t calculate_capacity(PARROT_INTERP, size_t needed)>

Calculate capacity for string. We allocate double the amount needed.

=cut

*/

PARROT_WARN_UNUSED_RESULT
PARROT_CONST_FUNCTION
static size_t
calculate_capacity(SHIM_INTERP, size_t needed)
{
    ASSERT_ARGS(calculate_capacity)

    needed *= 2;
    /* round up to 16 */
    needed  = (needed + 15) & ~15;

    return needed;
}

/*

=item C<static void convert_encoding(PARROT_INTERP, STR_VTABLE *dest_encoding,
STRING *buffer, size_t size_to_add)>

Convert buffer content to the encoding specified and increase its size,
reallocating it if needed.

=back

=cut

*/

static void
convert_encoding(PARROT_INTERP, ARGIN(STR_VTABLE *dest_encoding),
        ARGMOD(STRING *buffer), size_t size_to_add)
{
    ASSERT_ARGS(convert_encoding)
    STRING * new_buffer;
    size_t total_size;

    new_buffer = dest_encoding->to_encoding(interp, buffer);
    total_size = new_buffer->bufused + size_to_add;

    if (total_size > buffer->_buflen) {
        /* Reallocate */
        total_size = calculate_capacity(interp, total_size);
        Parrot_gc_reallocate_string_storage(interp, buffer, total_size);
    }
    buffer->bufused  = new_buffer->bufused;
    buffer->encoding = new_buffer->encoding;

    memcpy(buffer->strstart, new_buffer->strstart,
            new_buffer->bufused);
}

/*
 * Local variables:
 *   c-file-style: "parrot"
 * End:
 * vim: expandtab shiftwidth=4 cinoptions='\:2=2' :
 */