private Object interpolate()

in org.eclipse.sisu.inject/src/org/eclipse/sisu/wire/PlaceholderBeanProvider.java [130:174]

• 44 lines of code
• 14 McCabe index (conditional complexity)

    private Object interpolate( final String template, final Class<?> clazz )
    {
        final StringBuilder buf;
        if ( template.contains( "${" ) )
        {
            buf = new StringBuilder( template );
        }
        else if ( properties.containsKey( template ) )
        {
            // handle situations where someone missed out the main brackets
            buf = new StringBuilder( "${" ).append( template ).append( '}' );
        }
        else
        {
            return template; // nothing to interpolate, maintain reference
        }
        int x = 0, y, expressionEnd = 0, expressionNum = 0;
        while ( ( x = buf.indexOf( "${", x ) ) >= 0 && ( y = buf.indexOf( "}", x ) + 1 ) > 0 )
        {
            if ( y > expressionEnd ) // making progress
            {
                expressionNum = 0;
                expressionEnd = y;
            }
            final String key = buf.substring( x + 2, y - 1 );
            final int anchor = key.indexOf( ":-" );
            Object value = properties.get( anchor < 0 ? key : key.substring( 0, anchor ) );
            if ( value == null && anchor >= 0 )
            {
                value = key.substring( anchor + 2 );
            }
            if ( expressionNum++ >= EXPRESSION_RECURSION_LIMIT )
            {
                throw new ProvisionException( "Recursive configuration: " + template + " stopped at: " + buf );
            }
            final int len = buf.length();
            if ( 0 == x && len == y && String.class != clazz && clazz.isInstance( value ) )
            {
                return value; // found compatible (non-String) instance in the properties!
            }
            buf.replace( x, y, String.valueOf( value ) );
            expressionEnd += buf.length() - len;
        }
        return nullify( buf.toString() );
    }