mlt_properties.c, mlt_service.c: bugfix to make reference counting and service closur...

[melted] / src / framework / mlt_properties.c

/*
 * mlt_properties.c -- base properties class
 * Copyright (C) 2003-2004 Ushodaya Enterprises Limited
 * Author: Charles Yates <charles.yates@pandora.be>
 * Contributor: Dan Dennedy <dan@dennedy.org>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "mlt_properties.h"
#include "mlt_property.h"
#include "mlt_deque.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <stdarg.h>
#include <pthread.h>
#include <sys/types.h>
#include <dirent.h>

/* ---------------- // Private Implementation // ---------------- */

/** Private implementation of the property list.
*/

typedef struct
{
        int hash[ 199 ];
        char **name;
        mlt_property *value;
        int count;
        int size;
        mlt_properties mirror;
        int ref_count;
        pthread_mutex_t mutex;
}
property_list;

/** Memory leak checks.
*/

//#define _MLT_PROPERTY_CHECKS_ 2

#ifdef _MLT_PROPERTY_CHECKS_
static int properties_created = 0;
static int properties_destroyed = 0;
#endif

/** Basic implementation.
*/

int mlt_properties_init( mlt_properties this, void *child )
{
        if ( this != NULL )
        {
#ifdef _MLT_PROPERTY_CHECKS_
                // Increment number of properties created
                properties_created ++;
#endif

                // NULL all methods
                memset( this, 0, sizeof( struct mlt_properties_s ) );

                // Assign the child of the object
                this->child = child;

                // Allocate the local structure
                this->local = calloc( sizeof( property_list ), 1 );

                // Increment the ref count
                ( ( property_list * )this->local )->ref_count = 1;
                pthread_mutex_init( &( ( property_list * )this->local )->mutex, NULL );;
        }

        // Check that initialisation was successful
        return this != NULL && this->local == NULL;
}

/** Constructor for stand alone object.
*/

mlt_properties mlt_properties_new( )
{
        // Construct a standalone properties object
        mlt_properties this = calloc( sizeof( struct mlt_properties_s ), 1 );

        // Initialise this
        mlt_properties_init( this, NULL );

        // Return the pointer
        return this;
}

/** Load properties from a .properties file (DEPRECATED).
*/

mlt_properties mlt_properties_load( const char *filename )
{
        // Construct a standalone properties object
        mlt_properties this = mlt_properties_new( );

        if ( this != NULL )
        {
                // Open the file
                FILE *file = fopen( filename, "r" );

                // Load contents of file
                if ( file != NULL )
                {
                        // Temp string
                        char temp[ 1024 ];
                        char last[ 1024 ] = "";

                        // Read each string from the file
                        while( fgets( temp, 1024, file ) )
                        {
                                // Chomp the string
                                temp[ strlen( temp ) - 1 ] = '\0';

                                // Check if the line starts with a .
                                if ( temp[ 0 ] == '.' )
                                {
                                        char temp2[ 1024 ];
                                        sprintf( temp2, "%s%s", last, temp );
                                        strcpy( temp, temp2 );
                                }
                                else if ( strchr( temp, '=' ) )
                                {
                                        strcpy( last, temp );
                                        *( strchr( last, '=' ) ) = '\0';
                                }

                                // Parse and set the property
                                if ( strcmp( temp, "" ) && temp[ 0 ] != '#' )
                                        mlt_properties_parse( this, temp );
                        }

                        // Close the file
                        fclose( file );
                }
        }

        // Return the pointer
        return this;
}

static inline int generate_hash( const char *name )
{
        int hash = 0;
        int i = 1;
        while ( *name )
                hash = ( hash + ( i ++ * ( *name ++ & 31 ) ) ) % 199;
        return hash;
}

/** Special case - when a container (such as fezzik) is protecting another 
        producer, we need to ensure that properties are passed through to the
        real producer.
*/

static inline void mlt_properties_do_mirror( mlt_properties this, const char *name )
{
        property_list *list = this->local;
        if ( list->mirror != NULL ) 
        {
                char *value = mlt_properties_get( this, name );
                if ( value != NULL )
                        mlt_properties_set( list->mirror, name, value );
        }
}

/** Maintain ref count to allow multiple uses of an mlt object.
*/

int mlt_properties_inc_ref( mlt_properties this )
{
        int result = 0;
        if ( this != NULL )
        {
                property_list *list = this->local;
                pthread_mutex_lock( &list->mutex );
                result = ++ list->ref_count;
                pthread_mutex_unlock( &list->mutex );
        }
        return result;
}

/** Maintain ref count to allow multiple uses of an mlt object.
*/

int mlt_properties_dec_ref( mlt_properties this )
{
        int result = 0;
        if ( this != NULL )
        {
                property_list *list = this->local;
                pthread_mutex_lock( &list->mutex );
                result = -- list->ref_count;
                pthread_mutex_unlock( &list->mutex );
        }
        return result;
}

/** Return the ref count of this object.
*/

int mlt_properties_ref_count( mlt_properties this )
{
        if ( this != NULL )
        {
                property_list *list = this->local;
                return list->ref_count;
        }
        return 0;
}

/** Mirror properties set on 'this' to 'that'.
*/

void mlt_properties_mirror( mlt_properties this, mlt_properties that )
{
        property_list *list = this->local;
        list->mirror = that;
}

/** Inherit all serialisable properties from that into this.
*/

int mlt_properties_inherit( mlt_properties this, mlt_properties that )
{
        int count = mlt_properties_count( that );
        int i = 0;
        for ( i = 0; i < count; i ++ )
        {
                char *value = mlt_properties_get_value( that, i );
                if ( value != NULL )
                {
                        char *name = mlt_properties_get_name( that, i );
                        mlt_properties_set( this, name, value );
                }
        }
        return 0;
}

/** Pass all properties from 'that' that match the prefix to 'this' (excluding the prefix).
*/

int mlt_properties_pass( mlt_properties this, mlt_properties that, const char *prefix )
{
        int count = mlt_properties_count( that );
        int length = strlen( prefix );
        int i = 0;
        for ( i = 0; i < count; i ++ )
        {
                char *name = mlt_properties_get_name( that, i );
                if ( !strncmp( name, prefix, length ) )
                {
                        char *value = mlt_properties_get_value( that, i );
                        if ( value != NULL )
                                mlt_properties_set( this, name + length, value );
                }
        }
        return 0;
}

/** Locate a property by name
*/

static inline mlt_property mlt_properties_find( mlt_properties this, const char *name )
{
        property_list *list = this->local;
        mlt_property value = NULL;
        int key = generate_hash( name );
        int i = list->hash[ key ] - 1;

        if ( i >= 0 )
        {
                // Check if we're hashed
                if ( list->count > 0 &&
                        name[ 0 ] == list->name[ i ][ 0 ] && 
                        !strcmp( list->name[ i ], name ) )
                        value = list->value[ i ];

                // Locate the item 
                for ( i = list->count - 1; value == NULL && i >= 0; i -- )
                        if ( name[ 0 ] == list->name[ i ][ 0 ] && !strcmp( list->name[ i ], name ) )
                                value = list->value[ i ];
        }

        return value;
}

/** Add a new property.
*/

static mlt_property mlt_properties_add( mlt_properties this, const char *name )
{
        property_list *list = this->local;
        int key = generate_hash( name );

        // Check that we have space and resize if necessary
        if ( list->count == list->size )
        {
                list->size += 50;
                list->name = realloc( list->name, list->size * sizeof( const char * ) );
                list->value = realloc( list->value, list->size * sizeof( mlt_property ) );
        }

        // Assign name/value pair
        list->name[ list->count ] = strdup( name );
        list->value[ list->count ] = mlt_property_init( );

        // Assign to hash table
        if ( list->hash[ key ] == 0 )
                list->hash[ key ] = list->count + 1;

        // Return and increment count accordingly
        return list->value[ list->count ++ ];
}

/** Fetch a property by name - this includes add if not found.
*/

static mlt_property mlt_properties_fetch( mlt_properties this, const char *name )
{
        // Try to find an existing property first
        mlt_property property = mlt_properties_find( this, name );

        // If it wasn't found, create one
        if ( property == NULL )
                property = mlt_properties_add( this, name );

        // Return the property
        return property;
}

/** Pass property 'name' from 'that' to 'this' 
* Who to blame: Zach <zachary.drew@gmail.com>
*/

void mlt_properties_pass_property( mlt_properties this, mlt_properties that, const char *name )
{
        // Make sure the source property isn't null.
        mlt_property that_prop = mlt_properties_find( that, name );
        if( that_prop == NULL )
                return;

        mlt_property_pass( mlt_properties_fetch( this, name ), that_prop );
}

/** Pass all properties from 'that' to 'this' as found in comma seperated 'list'.
* Who to blame: Zach <zachary.drew@gmail.com>
*/

int mlt_properties_pass_list( mlt_properties this, mlt_properties that, const char *list )
{
        char *props = strdup( list );
        char *ptr = props;
        char *delim = " ,\t\n"; // Any combination of spaces, commas, tabs, and newlines
        int count, done = 0;

        while( !done )
        {
                count = strcspn( ptr, delim );

                if( ptr[count] == '\0' )
                        done = 1;
                else
                        ptr[count] = '\0';      // Make it a real string

                mlt_properties_pass_property( this, that, ptr );

                ptr += count + 1;
                ptr += strspn( ptr, delim );
        }

        free( props );

        return 0;
}


/** Set the property.
*/

int mlt_properties_set( mlt_properties this, const char *name, const char *value )
{
        int error = 1;

        // Fetch the property to work with
        mlt_property property = mlt_properties_fetch( this, name );

        // Set it if not NULL
        if ( property == NULL )
        {
                fprintf( stderr, "Whoops - %s not found (should never occur)\n", name );
        }
        else if ( value == NULL )
        {
                error = mlt_property_set_string( property, value );
                mlt_properties_do_mirror( this, name );
        }
        else if ( *value != '@' )
        {
                error = mlt_property_set_string( property, value );
                mlt_properties_do_mirror( this, name );
        }
        else if ( value[ 0 ] == '@' )
        {
                double total = 0;
                double current = 0;
                char id[ 255 ];
                char op = '+';

                value ++;

                while ( *value != '\0' )
                {
                        int length = strcspn( value, "+-*/" );

                        // Get the identifier
                        strncpy( id, value, length );
                        id[ length ] = '\0';
                        value += length;

                        // Determine the value
                        if ( isdigit( id[ 0 ] ) )
                                current = atof( id );
                        else
                                current = mlt_properties_get_double( this, id );

                        // Apply the operation
                        switch( op )
                        {
                                case '+':
                                        total += current;
                                        break;
                                case '-':
                                        total -= current;
                                        break;
                                case '*':
                                        total *= current;
                                        break;
                                case '/':
                                        total = total / current;
                                        break;
                        }

                        // Get the next op
                        op = *value != '\0' ? *value ++ : ' ';
                }

                error = mlt_property_set_double( property, total );
                mlt_properties_do_mirror( this, name );
        }

        mlt_events_fire( this, "property-changed", name, NULL );

        return error;
}

/** Set or default the property.
*/

int mlt_properties_set_or_default( mlt_properties this, const char *name, const char *value, const char *def )
{
        return mlt_properties_set( this, name, value == NULL ? def : value );
}

/** Get a string value by name.
*/

char *mlt_properties_get( mlt_properties this, const char *name )
{
        mlt_property value = mlt_properties_find( this, name );
        return value == NULL ? NULL : mlt_property_get_string( value );
}

/** Get a name by index.
*/

char *mlt_properties_get_name( mlt_properties this, int index )
{
        property_list *list = this->local;
        if ( index >= 0 && index < list->count )
                return list->name[ index ];
        return NULL;
}

/** Get a string value by index.
*/

char *mlt_properties_get_value( mlt_properties this, int index )
{
        property_list *list = this->local;
        if ( index >= 0 && index < list->count )
                return mlt_property_get_string( list->value[ index ] );
        return NULL;
}

/** Get a data value by index.
*/

void *mlt_properties_get_data_at( mlt_properties this, int index, int *size )
{
        property_list *list = this->local;
        if ( index >= 0 && index < list->count )
                return mlt_property_get_data( list->value[ index ], size );
        return NULL;
}

/** Return the number of items in the list.
*/

int mlt_properties_count( mlt_properties this )
{
        property_list *list = this->local;
        return list->count;
}

/** Set a value by parsing a name=value string
*/

int mlt_properties_parse( mlt_properties this, const char *namevalue )
{
        char *name = strdup( namevalue );
        char *value = NULL;
        int error = 0;
        char *ptr = strchr( name, '=' );

        if ( ptr )
        {
                *( ptr ++ ) = '\0';

                if ( *ptr != '\"' )
                {
                        value = strdup( ptr );
                }
                else
                {
                        ptr ++;
                        value = strdup( ptr );
                        if ( value != NULL && value[ strlen( value ) - 1 ] == '\"' )
                                value[ strlen( value ) - 1 ] = '\0';
                }
        }
        else
        {
                value = strdup( "" );
        }

        error = mlt_properties_set( this, name, value );

        free( name );
        free( value );

        return error;
}

/** Get a value associated to the name.
*/

int mlt_properties_get_int( mlt_properties this, const char *name )
{
        mlt_property value = mlt_properties_find( this, name );
        return value == NULL ? 0 : mlt_property_get_int( value );
}

/** Set a value associated to the name.
*/

int mlt_properties_set_int( mlt_properties this, const char *name, int value )
{
        int error = 1;

        // Fetch the property to work with
        mlt_property property = mlt_properties_fetch( this, name );

        // Set it if not NULL
        if ( property != NULL )
        {
                error = mlt_property_set_int( property, value );
                mlt_properties_do_mirror( this, name );
        }

        mlt_events_fire( this, "property-changed", name, NULL );

        return error;
}

/** Get a value associated to the name.
*/

int64_t mlt_properties_get_int64( mlt_properties this, const char *name )
{
        mlt_property value = mlt_properties_find( this, name );
        return value == NULL ? 0 : mlt_property_get_int64( value );
}

/** Set a value associated to the name.
*/

int mlt_properties_set_int64( mlt_properties this, const char *name, int64_t value )
{
        int error = 1;

        // Fetch the property to work with
        mlt_property property = mlt_properties_fetch( this, name );

        // Set it if not NULL
        if ( property != NULL )
        {
                error = mlt_property_set_int64( property, value );
                mlt_properties_do_mirror( this, name );
        }

        mlt_events_fire( this, "property-changed", name, NULL );

        return error;
}

/** Get a value associated to the name.
*/

double mlt_properties_get_double( mlt_properties this, const char *name )
{
        mlt_property value = mlt_properties_find( this, name );
        return value == NULL ? 0 : mlt_property_get_double( value );
}

/** Set a value associated to the name.
*/

int mlt_properties_set_double( mlt_properties this, const char *name, double value )
{
        int error = 1;

        // Fetch the property to work with
        mlt_property property = mlt_properties_fetch( this, name );

        // Set it if not NULL
        if ( property != NULL )
        {
                error = mlt_property_set_double( property, value );
                mlt_properties_do_mirror( this, name );
        }

        mlt_events_fire( this, "property-changed", name, NULL );

        return error;
}

/** Get a value associated to the name.
*/

mlt_position mlt_properties_get_position( mlt_properties this, const char *name )
{
        mlt_property value = mlt_properties_find( this, name );
        return value == NULL ? 0 : mlt_property_get_position( value );
}

/** Set a value associated to the name.
*/

int mlt_properties_set_position( mlt_properties this, const char *name, mlt_position value )
{
        int error = 1;

        // Fetch the property to work with
        mlt_property property = mlt_properties_fetch( this, name );

        // Set it if not NULL
        if ( property != NULL )
        {
                error = mlt_property_set_position( property, value );
                mlt_properties_do_mirror( this, name );
        }

        mlt_events_fire( this, "property-changed", name, NULL );

        return error;
}

/** Get a value associated to the name.
*/

void *mlt_properties_get_data( mlt_properties this, const char *name, int *length )
{
        mlt_property value = mlt_properties_find( this, name );
        return value == NULL ? NULL : mlt_property_get_data( value, length );
}

/** Set a value associated to the name.
*/

int mlt_properties_set_data( mlt_properties this, const char *name, void *value, int length, mlt_destructor destroy, mlt_serialiser serialise )
{
        int error = 1;

        // Fetch the property to work with
        mlt_property property = mlt_properties_fetch( this, name );

        // Set it if not NULL
        if ( property != NULL )
                error = mlt_property_set_data( property, value, length, destroy, serialise );

        mlt_events_fire( this, "property-changed", name, NULL );

        return error;
}

/** Rename a property.
*/

int mlt_properties_rename( mlt_properties this, const char *source, const char *dest )
{
        mlt_property value = mlt_properties_find( this, dest );

        if ( value == NULL )
        {
                property_list *list = this->local;
                int i = 0;

                // Locate the item 
                for ( i = 0; i < list->count; i ++ )
                {
                        if ( !strcmp( list->name[ i ], source ) )
                        {
                                free( list->name[ i ] );
                                list->name[ i ] = strdup( dest );
                                list->hash[ generate_hash( dest ) ] = i + 1;
                                break;
                        }
                }
        }

        return value != NULL;
}

/** Dump the properties.
*/

void mlt_properties_dump( mlt_properties this, FILE *output )
{
        property_list *list = this->local;
        int i = 0;
        for ( i = 0; i < list->count; i ++ )
                if ( mlt_properties_get( this, list->name[ i ] ) != NULL )
                        fprintf( output, "%s=%s\n", list->name[ i ], mlt_properties_get( this, list->name[ i ] ) );
}

void mlt_properties_debug( mlt_properties this, const char *title, FILE *output )
{
        if ( output == NULL ) output = stderr;
        fprintf( output, "%s: ", title );
        if ( this != NULL )
        {
                property_list *list = this->local;
                int i = 0;
                fprintf( output, "[ ref=%d", list->ref_count );
                for ( i = 0; i < list->count; i ++ )
                        if ( mlt_properties_get( this, list->name[ i ] ) != NULL )
                                fprintf( output, ", %s=%s", list->name[ i ], mlt_properties_get( this, list->name[ i ] ) );
                        else
                                fprintf( output, ", %s=%p", list->name[ i ], mlt_properties_get_data( this, list->name[ i ], NULL ) );
                fprintf( output, " ]" );
        }
        fprintf( output, "\n" );
}

int mlt_properties_save( mlt_properties this, const char *filename )
{
        int error = 1;
        FILE *f = fopen( filename, "w" );
        if ( f != NULL )
        {
                mlt_properties_dump( this, f );
                fclose( f );
                error = 0;
        }
        return error;
}

/* This is a very basic cross platform fnmatch replacement - it will fail in
** many cases, but for the basic *.XXX and YYY*.XXX, it will work ok.
*/

static int mlt_fnmatch( const char *wild, const char *file )
{
        int f = 0;
        int w = 0;

        while( f < strlen( file ) && w < strlen( wild ) )
        {
                if ( wild[ w ] == '*' )
                {
                        w ++;
                        if ( w == strlen( wild ) )
                                f = strlen( file );
                        while ( f != strlen( file ) && tolower( file[ f ] ) != tolower( wild[ w ] ) )
                                f ++;
                }
                else if ( wild[ w ] == '?' || tolower( file[ f ] ) == tolower( wild[ w ] ) )
                {
                        f ++;
                        w ++;
                }
                else if ( wild[ 0 ] == '*' )
                {
                        w = 0;
                }
                else
                {
                        return 0;
                }
        }

        return strlen( file ) == f &&  strlen( wild ) == w;
}

static int mlt_compare( const void *this, const void *that )
{
        return strcmp( mlt_property_get_string( *( mlt_property * )this ), mlt_property_get_string( *( mlt_property * )that ) );
}

/* Obtains an optionally sorted list of the files found in a directory with a specific wild card.
 * Entries in the list have a numeric name (running from 0 to count - 1). Only values change
 * position if sort is enabled. Designed to be posix compatible (linux, os/x, mingw etc).
 */

int mlt_properties_dir_list( mlt_properties this, const char *dirname, const char *pattern, int sort )
{
        DIR *dir = opendir( dirname );

        if ( dir )
        {
                char key[ 20 ];
                struct dirent *de = readdir( dir );
                char fullname[ 1024 ];
                while( de != NULL )
                {
                        sprintf( key, "%d", mlt_properties_count( this ) );
                        snprintf( fullname, 1024, "%s/%s", dirname, de->d_name );
                        if ( pattern == NULL )
                                mlt_properties_set( this, key, fullname );
                        else if ( de->d_name[ 0 ] != '.' && mlt_fnmatch( pattern, de->d_name ) )
                                mlt_properties_set( this, key, fullname );
                        de = readdir( dir );
                }

                closedir( dir );
        }

        if ( sort && mlt_properties_count( this ) )
        {
                property_list *list = this->local;
                qsort( list->value, mlt_properties_count( this ), sizeof( mlt_property ), mlt_compare );
        }

        return mlt_properties_count( this );
}

/** Close the list.
*/

void mlt_properties_close( mlt_properties this )
{
        if ( this != NULL && mlt_properties_dec_ref( this ) <= 0 )
        {
                if ( this->close != NULL )
                {
                        this->close( this->close_object );
                }
                else
                {
                        property_list *list = this->local;
                        int index = 0;

#if _MLT_PROPERTY_CHECKS_ == 1
                        // Show debug info
                        mlt_properties_debug( this, "Closing", stderr );
#endif

#ifdef _MLT_PROPERTY_CHECKS_
                        // Increment destroyed count
                        properties_destroyed ++;

                        // Show current stats - these should match when the app is closed
                        fprintf( stderr, "Created %d, destroyed %d\n", properties_created, properties_destroyed );
#endif

                        // Clean up names and values
                        for ( index = list->count - 1; index >= 0; index -- )
                        {
                                free( list->name[ index ] );
                                mlt_property_close( list->value[ index ] );
                        }
        
                        // Clear up the list
                        pthread_mutex_destroy( &list->mutex );
                        free( list->name );
                        free( list->value );
                        free( list );
        
                        // Free this now if this has no child
                        if ( this->child == NULL )
                                free( this );
                }
        }
}

/** Determine if the properties list is really just a sequence or ordered list.
    Returns 0 if false or 1 if true.
*/
int mlt_properties_is_sequence( mlt_properties properties )
{
        int i;
        int n = mlt_properties_count( properties );
        for ( i = 0; i < n; i++ )
                if ( ! isdigit( mlt_properties_get_name( properties, i )[0] ) )
                        return 0;
        return 1;
}

/** YAML Tiny Parser
 * YAML is a nifty text format popular in the Ruby world as a cleaner,
 * less verbose alternative to XML. See this Wikipedia topic for an overview:
 * http://en.wikipedia.org/wiki/YAML
 * The YAML specification is at:
 * http://yaml.org/
 * YAML::Tiny is a Perl module that specifies a subset of YAML that we are
 * using here (for the same reasons):
 * http://search.cpan.org/~adamk/YAML-Tiny-1.25/lib/YAML/Tiny.pm
 */

struct yaml_parser_context
{
        mlt_deque stack;
        unsigned int level;
        unsigned int index;
        char block;
        char *block_name;
        unsigned int block_indent;
        
};
typedef struct yaml_parser_context *yaml_parser;

static unsigned int ltrim( char **s )
{
        unsigned int i = 0;
        char *c = *s;
        int n = strlen( c );
        for ( i = 0; i < n && *c == ' '; i++, c++ );
        *s = c;
        return i;
}

static unsigned int rtrim( char *s )
{
        int n = strlen( s );
        int i;
        for ( i = n; i > 0 && s[i - 1] == ' '; --i )
                s[i - 1] = 0;
        return n - i;
}

static int parse_yaml( yaml_parser context, const char *namevalue )
{
        char *name_ = strdup( namevalue );
        char *name = name_;
        char *value = NULL;
        int error = 0;
        char *ptr = strchr( name, ':' );
        unsigned int indent = ltrim( &name );
        mlt_properties properties = mlt_deque_peek_front( context->stack );
        
        // Ascending one more levels in the tree
        if ( indent < context->level )
        {
                unsigned int i;
                unsigned int n = ( context->level - indent ) / 2;
                for ( i = 0; i < n; i++ )
                        mlt_deque_pop_front( context->stack );
                properties = mlt_deque_peek_front( context->stack );
                context->level = indent;
        }
        
        // Descending a level in the tree
        else if ( indent > context->level && context->block == 0 )
        {
                context->level = indent;
        }
        
        // If there is a colon that is not part of a block
        if ( ptr && ( indent == context->level ) )
        {
                // Reset block processing
                if ( context->block_name )
                {
                        free( context->block_name );
                        context->block_name = NULL;
                        context->block = 0;
                }
                
                // Terminate the name and setup the value pointer
                *( ptr ++ ) = 0;
                
                // Trim comment
                char *comment = strchr( ptr, '#' );
                if ( comment )
                {
                        *comment = 0;
                }
                
                // Trim leading and trailing spaces from bare value 
                ltrim( &ptr );
                rtrim( ptr );
                
                // No value means a child
                if ( strcmp( ptr, "" ) == 0 )
                {
                        mlt_properties child = mlt_properties_new();
                        mlt_properties_set_data( properties, name, child, 0, 
                                ( mlt_destructor )mlt_properties_close, NULL );
                        mlt_deque_push_front( context->stack, child );
                        context->index = 0;
                        free( name_ );
                        return error;
                }
                
                // A dash indicates a sequence item
                if ( name[0] == '-' )
                {
                        mlt_properties child = mlt_properties_new();
                        char key[20];
                        
                        snprintf( key, sizeof(key), "%d", context->index++ );
                        mlt_properties_set_data( properties, key, child, 0, 
                                ( mlt_destructor )mlt_properties_close, NULL );
                        mlt_deque_push_front( context->stack, child );

                        name ++;
                        context->level += ltrim( &name ) + 1;
                        properties = child;
                }
                
                // Value is quoted
                if ( *ptr == '\"' )
                {
                        ptr ++;
                        value = strdup( ptr );
                        if ( value && value[ strlen( value ) - 1 ] == '\"' )
                                value[ strlen( value ) - 1 ] = 0;
                }
                
                // Value is folded or unfolded block
                else if ( *ptr == '|' || *ptr == '>' )
                {
                        context->block = *ptr;
                        context->block_name = strdup( name );
                        context->block_indent = 0;
                        value = strdup( "" );
                }
                
                // Bare value
                else
                {
                        value = strdup( ptr );
                }
        }
        
        // A list of scalars
        else if ( name[0] == '-' )
        {
                // Reset block processing
                if ( context->block_name )
                {
                        free( context->block_name );
                        context->block_name = NULL;
                        context->block = 0;
                }
                
                char key[20];
                
                snprintf( key, sizeof(key), "%d", context->index++ );
                ptr = name + 1;
                
                // Trim comment
                char *comment = strchr( ptr, '#' );
                if ( comment )
                        *comment = 0;
                
                // Trim leading and trailing spaces from bare value 
                ltrim( &ptr );
                rtrim( ptr );
                
                // Value is quoted
                if ( *ptr == '\"' )
                {
                        ptr ++;
                        value = strdup( ptr );
                        if ( value && value[ strlen( value ) - 1 ] == '\"' )
                                value[ strlen( value ) - 1 ] = 0;
                }
                
                // Value is folded or unfolded block
                else if ( *ptr == '|' || *ptr == '>' )
                {
                        context->block = *ptr;
                        context->block_name = strdup( key );
                        context->block_indent = 0;
                        value = strdup( "" );
                }
                
                // Bare value
                else
                {
                        value = strdup( ptr );
                }
                
                free( name_ );
                name = name_ = strdup( key );
        }

        // Non-folded block
        else if ( context->block == '|' )
        {
                if ( context->block_indent == 0 )
                        context->block_indent = indent;
                if ( indent > context->block_indent )
                        name = &name_[ context->block_indent ];
                rtrim( name );
                char *old_value = mlt_properties_get( properties, context->block_name );
                value = calloc( 1, strlen( old_value ) + strlen( name ) + 2 );
                strcpy( value, old_value );
                if ( strcmp( old_value, "" ) )
                        strcat( value, "\n" );
                strcat( value, name );
                name = context->block_name;
        }
        
        // Folded block
        else if ( context->block == '>' )
        {
                ltrim( &name );
                rtrim( name );
                char *old_value = mlt_properties_get( properties, context->block_name );
                
                // Blank line (prepended with spaces) is new line
                if ( strcmp( name, "" ) == 0 )
                {
                        value = calloc( 1, strlen( old_value ) + 2 );
                        strcat( value, old_value );
                        strcat( value, "\n" );
                }
                // Concatenate with space
                else
                {
                        value = calloc( 1, strlen( old_value ) + strlen( name ) + 2 );
                        strcat( value, old_value );
                        if ( strcmp( old_value, "" ) && old_value[ strlen( old_value ) - 1 ] != '\n' )
                                strcat( value, " " );
                        strcat( value, name );
                }
                name = context->block_name;
        }
        
        else
        {
                value = strdup( "" );
        }

        error = mlt_properties_set( properties, name, value );

        free( name_ );
        free( value );

        return error;
}

mlt_properties mlt_properties_parse_yaml( const char *filename )
{
        // Construct a standalone properties object
        mlt_properties this = mlt_properties_new( );

        if ( this )
        {
                // Open the file
                FILE *file = fopen( filename, "r" );

                // Load contents of file
                if ( file )
                {
                        // Temp string
                        char temp[ 1024 ];
                        char *ptemp = &temp[ 0 ];
                        
                        // Parser context
                        yaml_parser context = calloc( 1, sizeof( struct yaml_parser_context ) );
                        context->stack = mlt_deque_init();
                        mlt_deque_push_front( context->stack, this );

                        // Read each string from the file
                        while( fgets( temp, 1024, file ) )
                        {
                                // Check for end-of-stream
                                if ( strncmp( ptemp, "...", 3 ) == 0 )
                                        break;
                                        
                                // Chomp the string
                                temp[ strlen( temp ) - 1 ] = '\0';

                                // Skip blank lines, comment lines, and document separator
                                if ( strcmp( ptemp, "" ) && ptemp[ 0 ] != '#' && strncmp( ptemp, "---", 3 ) 
                                     && strncmp( ptemp, "%YAML", 5 ) && strncmp( ptemp, "% YAML", 6 ) )
                                        parse_yaml( context, temp );
                        }

                        // Close the file
                        fclose( file );
                        mlt_deque_close( context->stack );
                        if ( context->block_name )
                                free( context->block_name );
                        free( context );
                }
        }

        // Return the pointer
        return this;
}

/** YAML Tiny Serialiser
*/

/* strbuf is a self-growing string buffer */

#define STRBUF_GROWTH (1024)

struct strbuf_s
{
        size_t size;
        char *string;
};

typedef struct strbuf_s *strbuf;

static strbuf strbuf_new( )
{
        strbuf buffer = calloc( 1, sizeof( struct strbuf_s ) );
        buffer->size = STRBUF_GROWTH;
        buffer->string = calloc( 1, buffer->size );
        return buffer;
}

static void strbuf_close( strbuf buffer )
{
        // We do not free buffer->string; strbuf user must save that pointer
        // and free it.
        if ( buffer )
                free( buffer );
}

static char *strbuf_printf( strbuf buffer, const char *format, ... )
{
        while ( buffer->string )
        {
                va_list ap;
                va_start( ap, format );
                size_t len = strlen( buffer->string );
                size_t remain = buffer->size - len - 1;
                int need = vsnprintf( buffer->string + len, remain, format, ap );
                va_end( ap );
                if ( need > -1 && need < remain )
                        break;
                buffer->string[ len ] = 0;
                buffer->size += need + STRBUF_GROWTH;
                buffer->string = realloc( buffer->string, buffer->size );
        }
        return buffer->string;
}

static inline void indent_yaml( strbuf output, int indent )
{
        int j;
        for ( j = 0; j < indent; j++ )
                strbuf_printf( output, " " );
}

static void output_yaml_block_literal( strbuf output, const char *value, int indent )
{
        char *v = strdup( value );
        char *sol = v;
        char *eol = strchr( sol, '\n' );
        
        while ( eol )
        {
                indent_yaml( output, indent );
                *eol = '\0';
                strbuf_printf( output, "%s\n", sol );
                sol = eol + 1;
                eol = strchr( sol, '\n' );
        }       
        indent_yaml( output, indent );
        strbuf_printf( output, "%s\n", sol );
}

static void serialise_yaml( mlt_properties this, strbuf output, int indent, int is_parent_sequence )
{
        property_list *list = this->local;
        int i = 0;
        
        for ( i = 0; i < list->count; i ++ )
        {
                // This implementation assumes that all data elements are property lists.
                // Unfortunately, we do not have run time type identification.
                mlt_properties child = mlt_property_get_data( list->value[ i ], NULL );
                
                if ( mlt_properties_is_sequence( this ) )
                {
                        // Ignore hidden/non-serialisable items
                        if ( list->name[ i ][ 0 ] != '_' )
                        {
                                // Indicate a sequence item
                                indent_yaml( output, indent );
                                strbuf_printf( output, "- " );
                                
                                // If the value can be represented as a string
                                const char *value = mlt_properties_get( this, list->name[ i ] );
                                if ( value && strcmp( value, "" ) )
                                {
                                        // Determine if this is an unfolded block literal
                                        if ( strchr( value, '\n' ) )
                                        {
                                                strbuf_printf( output, "|\n" );
                                                output_yaml_block_literal( output, value, indent + strlen( list->name[ i ] ) + strlen( "|" ) );
                                        }
                                        else
                                        {
                                                strbuf_printf( output, "%s\n", value );
                                        }
                                }
                        }
                        // Recurse on child
                        if ( child )
                                serialise_yaml( child, output, indent + 2, 1 );
                }
                else 
                {
                        // Assume this is a normal map-oriented properties list
                        const char *value = mlt_properties_get( this, list->name[ i ] );
                        
                        // Ignore hidden/non-serialisable items
                        // If the value can be represented as a string
                        if ( list->name[ i ][ 0 ] != '_' && value && strcmp( value, "" ) )
                        {
                                if ( is_parent_sequence == 0 )
                                        indent_yaml( output, indent );
                                else
                                        is_parent_sequence = 0;
                                
                                // Determine if this is an unfolded block literal
                                if ( strchr( value, '\n' ) )
                                {
                                        strbuf_printf( output, "%s: |\n", list->name[ i ] );
                                        output_yaml_block_literal( output, value, indent + strlen( list->name[ i ] ) + strlen( ": " ) );
                                }
                                else
                                {
                                        strbuf_printf( output, "%s: %s\n", list->name[ i ], value );
                                }
                        }
                        
                        // Output a child as a map item
                        if ( child )
                        {
                                indent_yaml( output, indent );
                                strbuf_printf( output, "%s:\n", list->name[ i ] );

                                // Recurse on child
                                serialise_yaml( child, output, indent + 2, 0 );
                        }
                }
        }
}

/** Serialise the properties as a string of YAML Tiny.
    The caller must free the returned string.
*/

char *mlt_properties_serialise_yaml( mlt_properties this )
{
        strbuf b = strbuf_new();
        strbuf_printf( b, "---\n" );
        serialise_yaml( this, b, 0, 0 );
        strbuf_printf( b, "...\n" );
        char *ret = b->string;
        strbuf_close( b );
        return ret;
}