schema.java

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     * The type of the column with the given name.
     * @param field the column name
     * @return the column type
     */
    public Class getColumnType(String field) {
        int idx = getColumnIndex(field);
        return ( idx<0 ? null : m_types[idx] );
    }
    
    /**
     * The default value of the column at the given position.
     * @param col the column index
     * @return the column's default value
     */
    public Object getDefault(int col) {
        return m_dflts[col];
    }
    
    /**
     * The default value of the column with the given name.
     * @param field the column name
     * @return the column's default value
     */
    public Object getDefault(String field) {
        int idx = getColumnIndex(field);
        return ( idx<0 ? null : m_dflts[idx] );
    }
    
    /**
     * Set the default value for the given field.
     * @param col the column index of the field to set the default for
     * @param val the new default value
     */
    public void setDefault(int col, Object val) {
        // check lock status
        if ( m_locked ) {
            throw new IllegalStateException(
                "Can not update default values of a locked Schema.");
        }
        m_dflts[col] = val;
    }
    
    /**
     * Set the default value for the given field.
     * @param field the name of column to set the default for
     * @param val the new default value
     */
    public void setDefault(String field, Object val) {
        // check lock status
        if ( m_locked ) {
            throw new IllegalStateException(
                "Can not update default values of a locked Schema.");
        }
        int idx = getColumnIndex(field);
        m_dflts[idx] = val;
    }
    
    /**
     * Set the default value for the given field as an int.
     * @param field the name of column to set the default for
     * @param val the new default value
     */
    public void setDefault(String field, int val) {
        setDefault(field, new Integer(val));
    }
    
    /**
     * Set the default value for the given field as a long.
     * @param field the name of column to set the default for
     * @param val the new default value
     */
    public void setDefault(String field, long val) {
        setDefault(field, new Long(val));
    }
    
    /**
     * Set the default value for the given field as a float.
     * @param field the name of column to set the default for
     * @param val the new default value
     */
    public void setDefault(String field, float val) {
        setDefault(field, new Float(val));
    }
    
    /**
     * Set the default value for the given field as a double.
     * @param field the name of column to set the default for
     * @param val the new default value
     */
    public void setDefault(String field, double val) {
        setDefault(field, new Double(val));
    }
    
    /**
     * Set the default value for the given field as a boolean.
     * @param field the name of column to set the default for
     * @param val the new default value
     */
    public void setDefault(String field, boolean val) {
        setDefault(field, val ? Boolean.TRUE : Boolean.FALSE);
    }
    
    /**
     * Set default values for the current, start, and end columns of an
     * interpolated column.
     * @param field the field name of the interpolated column
     * @param val the new default value for all three implicated columns
     */
    public void setInterpolatedDefault(String field, Object val) {
        setDefault(field, val);
        setDefault(PrefuseLib.getStartField(field), val);
        setDefault(PrefuseLib.getEndField(field), val);
    }
    
    /**
     * Set default values for the current, start, and end columns of an
     * interpolated column as an int.
     * @param field the field name of the interpolated column
     * @param val the new default value for all three implicated columns
     */
    public void setInterpolatedDefault(String field, int val) {
        setInterpolatedDefault(field, new Integer(val));
    }
    
    /**
     * Set default values for the current, start, and end columns of an
     * interpolated column as a long.
     * @param field the field name of the interpolated column
     * @param val the new default value for all three implicated columns
     */
    public void setInterpolatedDefault(String field, long val) {
        setInterpolatedDefault(field, new Long(val));
    }
    
    /**
     * Set default values for the current, start, and end columns of an
     * interpolated column as a float.
     * @param field the field name of the interpolated column
     * @param val the new default value for all three implicated columns
     */
    public void setInterpolatedDefault(String field, float val) {
        setInterpolatedDefault(field, new Float(val));
    }
    
    /**
     * Set default values for the current, start, and end columns of an
     * interpolated column as a double.
     * @param field the field name of the interpolated column
     * @param val the new default value for all three implicated columns
     */
    public void setInterpolatedDefault(String field, double val) {
        setInterpolatedDefault(field, new Double(val));
    }
    
    /**
     * Set default values for the current, start, and end columns of an
     * interpolated column as a boolean.
     * @param field the field name of the interpolated column
     * @param val the new default value for all three implicated columns
     */
    public void setInterpolatedDefault(String field, boolean val) {
        setInterpolatedDefault(field, val ? Boolean.TRUE : Boolean.FALSE);
    }
    
    
    // ------------------------------------------------------------------------
    // Comparison and Hashing
    
    /**
     * Compares this schema with another one for equality.
     */
    public boolean equals(Object o) {
        if ( !(o instanceof Schema) )
            return false;
        
        Schema s = (Schema)o;
        if ( m_size != s.getColumnCount() )
            return false;
        
        for ( int i=0; i<m_size; ++i ) {
            if ( !(m_names[i].equals(s.getColumnName(i)) &&
                   m_types[i].equals(s.getColumnType(i)) &&
                   m_dflts[i].equals(s.getDefault(i))) )
            {
                return false;
            }
        }
        return true;
    }
    
    /**
     * Indicates if values from a given Schema can be safely assigned to
     * data using this Schema. The input Schema must be less than or
     * equal in length to this Schema, and all contained columns in the
     * given Schema must have matching names and types to this Schema.
     * This method does not consider default values settings or the
     * locked status of the Schemas. For example, if the given Schema
     * has different default values than this one, this will have no
     * impact on the assignability of the two.
     * @param s the input Schema
     * @return true if data models using this Schema could be assigned values
     * directly from data using the input Schema, false otherwise.
     */
    public boolean isAssignableFrom(Schema s) {
        int ssize = s.getColumnCount();
        
        if ( ssize > m_size )
            return false;
        
        for ( int i=0; i<ssize; ++i ) {
            int idx = getColumnIndex(s.getColumnName(i));
            if ( idx < 0 )
                return false;
            
            if ( !m_types[idx].equals(s.getColumnType(i)) )
                return false;
        }
        return true;
    }
    
    /**
     * Computes a hashcode for this schema.
     */
    public int hashCode() {
        int hashcode = 0;
        for ( int i=0; i<m_size; ++i ) {
            int idx = i+1;
            int code = idx*m_names[i].hashCode();
            code ^= idx*m_types[i].hashCode();
            if ( m_dflts[i] != null )
                code ^= m_dflts[i].hashCode();
            hashcode ^= code;
        }
        return hashcode;
    }
    
    /**
     * Returns a descriptive String for this schema.
     */
    public String toString() {
        StringBuffer sbuf = new StringBuffer();
        sbuf.append("Schema[");
        for ( int i=0; i<m_size; ++i ) {
            if ( i > 0 ) sbuf.append(' ');
            sbuf.append('(').append(m_names[i]).append(", ");
            sbuf.append(m_types[i].getName()).append(", ");
            sbuf.append(m_dflts[i]).append(')');
        }
        sbuf.append(']');
        return sbuf.toString();
    }
    
    // ------------------------------------------------------------------------
    // Table Operations
       
    /**
     * Instantiate this schema as a new Table instance.
     * @return a new Table with this schema
     */
    public Table instantiate() {
        return instantiate(0);
    }
    
    /**
     * Instantiate this schema as a new Table instance.
     * @param nrows the number of starting rows in the table
     * @return a new Table with this schema
     */
    public Table instantiate(int nrows) {
        Table t = new Table(nrows, m_size);
        for ( int i=0; i<m_size; ++i ) {
            t.addColumn(m_names[i], m_types[i], m_dflts[i]);
        }
        return t;
    }
    
} // end of class Schema