Code insertion completion

A computer-implemented method, comprising:

• representing a source code program during an edit session as a tree of non-terminal symbols and terminal symbols;
• accessing a code insertion state of the source code program, wherein the code insertion state includes a prefix, an insertion point and a suffix, wherein the insertion point represents a location in the source code program where one or more source code statements are to be inserted in between the prefix and the suffix, wherein the prefix and the suffix represent existing source code segments of the source code program;
• representing the code insertion state as a sequence of terminal symbols representing the prefix, a single statement non-terminal symbol representing a statement, and a sequence of terminal symbols representing the suffix;
• expanding the code insertion state into an insertion candidate representing the one or more source code statements to be inserted at the insertion point, wherein the expansion expands the single statement non-terminal symbol representing a statement iteratively into a series of new code states using production rules of a grammar of a programming language of the source code program until a stop expansion condition exists;
• utilizing a non-terminal selector model to select a non-terminal symbol of each new code state to expand and a non-terminal expansion model to select a production rule to expand the selected non-terminal symbol;
• and
• upon detection of the stop expansion condition, presenting the insertion candidate in the source code program.

A non-transitory computer-readable storage medium having instructions that when executed performs operations, comprising:

• accessing a non-terminal expansion model to predict a production rule of a grammar of a programming language to expand a non-terminal symbol;
• accessing a non-terminal selector model to predict a non-terminal symbol to expand;
• obtaining a code insertion state of a source code program, the code insertion state including an input sequence of terminal symbols representing a prefix, a single non-terminal statement symbol, and terminal symbols representing a suffix, wherein the single non-terminal statement symbol represents a location in the source code program to insert predicted source code statements in between the prefix and the suffix;
• decoding the single non-terminal statement symbol into the predicted source code statements by iteratively expanding the single non-terminal statement symbol into new code states, a new code state having terminal symbols and zero or more non-terminal symbols, wherein the expansion uses the non-terminal selector model to select a non-terminal symbol to expand at each iteration and the non-terminal expansion model to choose the production rule to expand each selected non-terminal symbol;
• and
• generating the predicted source code statements upon expansion of a select one of the new code states into a sequence of all terminal symbols.