示例#1
0
        /// <summary>
        /// This method can be called to obtain a DependsOnList for any DAX expression. This is useful when the
        /// user is currently editing the DAX expression of an object, but the expression has not been saved to
        /// the object.
        /// </summary>
        public static DependsOnList GetDependencies(IDaxDependantObject expressionObj, string dax, DAXProperty prop)
        {
            var dependsOn = new DependsOnList(null);

            ParseExpression(dax, expressionObj, prop, dependsOn);
            return(dependsOn);
        }
示例#2
0
        private static void ParseExpression(string dax, IDaxDependantObject expressionObj, DAXProperty prop, DependsOnList dependsOn = null)
        {
            var tokens = new DAXLexer(new AntlrInputStream(dax)).GetAllTokens();

            IToken lastTableRef    = null;
            int    startTableIndex = 0;

            for (var i = 0; i < tokens.Count; i++)
            {
                // TODO: This parsing could be used to check for invalid object references, for example to use in syntax highlighting or validation of expressions

                var tok = tokens[i];
                switch (tok.Type)
                {
                case DAXLexer.TABLE:
                case DAXLexer.TABLE_OR_VARIABLE:
                    if (i < tokens.Count - 1 && tokens[i + 1].Type == DAXLexer.COLUMN_OR_MEASURE)
                    {
                        // Keep the token reference, as the next token should be column (fully qualified).
                        lastTableRef    = tok;
                        startTableIndex = tok.StartIndex;
                    }
                    else
                    {
                        // Table referenced directly, don't save the reference for the next token.
                        lastTableRef = null;
                    }

                    if (Model.Tables.Contains(tok.Text.NoQ(true)))
                    {
                        if (dependsOn != null)
                        {
                            dependsOn.Add(Model.Tables[tok.Text.NoQ(true)], prop, tok.StartIndex, tok.StopIndex, true);
                        }
                        else
                        {
                            expressionObj.AddDep(Model.Tables[tok.Text.NoQ(true)], prop, tok.StartIndex, tok.StopIndex, true);
                        }
                    }
                    else
                    {
                        // Invalid reference (no table with that name) or possibly a variable or function ref
                    }
                    break;

                case DAXLexer.COLUMN_OR_MEASURE:
                    // Referencing a table just before the object reference
                    if (lastTableRef != null)
                    {
                        var tableName = lastTableRef.Text.NoQ(true);
                        lastTableRef = null;
                        if (!Model.Tables.Contains(tableName))
                        {
                            return;                                        // Invalid reference (no table with that name)
                        }
                        var table = Model.Tables[tableName];
                        // Referencing a column on a specific table
                        if (table.Columns.Contains(tok.Text.NoQ()))
                        {
                            if (dependsOn != null)
                            {
                                dependsOn.Add(table.Columns[tok.Text.NoQ()], prop, startTableIndex, tok.StopIndex, true);
                            }
                            else
                            {
                                expressionObj.AddDep(table.Columns[tok.Text.NoQ()], prop, startTableIndex, tok.StopIndex, true);
                            }
                        }
                        // Referencing a measure on a specific table
                        else if (table.Measures.Contains(tok.Text.NoQ()))
                        {
                            if (dependsOn != null)
                            {
                                dependsOn.Add(table.Measures[tok.Text.NoQ()], prop, startTableIndex, tok.StopIndex, true);
                            }
                            else
                            {
                                expressionObj.AddDep(table.Measures[tok.Text.NoQ()], prop, startTableIndex, tok.StopIndex, true);
                            }
                        }
                    }
                    // No table reference before the object reference
                    else
                    {
                        var table = (expressionObj as ITabularTableObject)?.Table;
                        // Referencing a column without specifying a table (assume column in same table):
                        if (table != null && table.Columns.Contains(tok.Text.NoQ()))
                        {
                            if (dependsOn != null)
                            {
                                dependsOn.Add(table.Columns[tok.Text.NoQ()], prop, tok.StartIndex, tok.StopIndex, false);
                            }
                            else
                            {
                                expressionObj.AddDep(table.Columns[tok.Text.NoQ()], prop, tok.StartIndex, tok.StopIndex, false);
                            }
                        }
                        // Referencing a measure or column without specifying a table
                        else
                        {
                            Measure m = null;
                            if (table != null && table.Measures.Contains(tok.Text.NoQ()))
                            {
                                m = table.Measures[tok.Text.NoQ()];
                            }
                            else
                            {
                                m = Model.Tables.FirstOrDefault(t => t.Measures.Contains(tok.Text.NoQ()))?.Measures[tok.Text.NoQ()];
                            }

                            if (m != null)
                            {
                                if (dependsOn != null)
                                {
                                    dependsOn.Add(m, prop, tok.StartIndex, tok.StopIndex, false);
                                }
                                else
                                {
                                    expressionObj.AddDep(m, prop, tok.StartIndex, tok.StopIndex, false);
                                }
                            }
                        }
                    }
                    break;

                default:
                    lastTableRef = null;
                    break;
                }
            }
        }