loki.expression.mappers

Mappers for traversing and transforming the Expression tree.

Classes

AttachScopesMapper([fail])	A Pymbolic expression mapper (i.e., a visitor for the expression tree) that determines the scope of TypedSymbol nodes and updates its scope pointer accordingly.
DetachScopesMapper()	A Pymbolic expression mapper (i.e., a visitor for the expression tree) that rebuilds an expression unchanged but with the scope for every TypedSymbol detached.
ExpressionCallbackMapper(callback, combine)	A visitor for expressions that returns the combined result of a specified callback function.
ExpressionDimensionsMapper()	A visitor for an expression that determines the dimensions of the expression.
ExpressionRetriever(query[, recurse_query])	A mapper for the expression tree that looks for entries specified by a query.
LokiIdentityMapper([invalidate_source])	A visitor to traverse and transform an expression tree
LokiStringifyMapper(*args, **kwargs)	A class derived from the default StringifyMapper that adds mappings for nodes of the expression tree that we added ourselves.
LokiWalkMapper()	A mapper that traverses the expression tree and calls visit() for each visited node.
SubstituteExpressionsMapper(expr_map[, ...])	A Pymbolic expression mapper (i.e., a visitor for the expression tree) that defines on-the-fly handlers from a given substitution map.

class LokiStringifyMapper(*args, **kwargs)

Bases: StringifyMapper

A class derived from the default StringifyMapper that adds mappings for nodes of the expression tree that we added ourselves.

This is the default pretty printer for nodes in the expression tree.

rec_with_force_parens_around(expr, *args, **kwargs)

map_logic_literal(expr, enclosing_prec, *args, **kwargs)

map_float_literal(expr, enclosing_prec, *args, **kwargs)

map_int_literal(expr, enclosing_prec, *args, **kwargs)

map_string_literal(expr, enclosing_prec, *args, **kwargs)

map_intrinsic_literal(expr, enclosing_prec, *args, **kwargs)

map_variable_symbol(expr, enclosing_prec, *args, **kwargs)

map_deferred_type_symbol(expr, enclosing_prec, *args, **kwargs)

map_procedure_symbol(expr, enclosing_prec, *args, **kwargs)

map_meta_symbol(expr, enclosing_prec, *args, **kwargs)

map_scalar(expr, enclosing_prec, *args, **kwargs)

map_array(expr, enclosing_prec, *args, **kwargs)

map_inline_call(expr, enclosing_prec, *args, **kwargs)

map_cast(expr, enclosing_prec, *args, **kwargs)

map_range(expr, enclosing_prec, *args, **kwargs)

map_range_index(expr, enclosing_prec, *args, **kwargs)

map_loop_range(expr, enclosing_prec, *args, **kwargs)

map_sum(expr, enclosing_prec, *args, **kwargs)

Since substraction and unary minus are mapped to multiplication with (-1), we are here looking for such cases and determine the matching operator for the output.

map_product(expr, enclosing_prec, *args, **kwargs)

map_quotient(expr, enclosing_prec, *args, **kwargs)

map_parenthesised_add(expr, enclosing_prec, *args, **kwargs)

map_parenthesised_mul(expr, enclosing_prec, *args, **kwargs)

map_parenthesised_div(expr, enclosing_prec, *args, **kwargs)

map_parenthesised_pow(expr, enclosing_prec, *args, **kwargs)

map_string_concat(expr, enclosing_prec, *args, **kwargs)

map_literal_list(expr, enclosing_prec, *args, **kwargs)

map_inline_do(expr, enclosing_prec, *args, **kwargs)

map_array_subscript(expr, enclosing_prec, *args, **kwargs)

map_string_subscript(expr, enclosing_prec, *args, **kwargs)

map_c_reference(expr, enclosing_prec, *args, **kwargs)

map_c_dereference(expr, enclosing_prec, *args, **kwargs)

class ExpressionRetriever(query, recurse_query=None, **kwargs)

Bases: LokiWalkMapper

A mapper for the expression tree that looks for entries specified by a query.

Parameters:

• query – Function handle that is given each visited expression node and yields True or False depending on whether that expression should be included into the result.

• recurse_query (optional) – Optional function handle to which each visited expression node is given and that should return True or False depending on whether that expression node and its children should be visited.

post_visit(expr, *args, **kwargs)

reset()

retrieve(expr, *args, **kwargs)

class ExpressionDimensionsMapper

Bases: Mapper

A visitor for an expression that determines the dimensions of the expression.

map_algebraic_leaf(expr, *args, **kwargs)

map_logic_literal(expr, *args, **kwargs)

map_float_literal(expr, *args, **kwargs)

map_int_literal(expr, *args, **kwargs)

map_string_literal(expr, *args, **kwargs)

map_intrinsic_literal(expr, *args, **kwargs)

map_variable_symbol(expr, *args, **kwargs)

map_scalar(expr, *args, **kwargs)

map_deferred_type_symbol(expr, *args, **kwargs)

map_array(expr, *args, **kwargs)

map_array_subscript(expr, *args, **kwargs)

map_string_subscript(expr, *args, **kwargs)

map_range_index(expr, *args, **kwargs)

map_sum(expr, *args, **kwargs)

map_product(expr, *args, **kwargs)

map_inline_do(expr, *args, **kwargs)

class ExpressionCallbackMapper(callback, combine)

Bases: CombineMapper

A visitor for expressions that returns the combined result of a specified callback function.

retrieve(expr, *args, **kwargs)

map_constant(expr, *args, **kwargs)

map_logic_literal(expr, *args, **kwargs)

map_string_literal(expr, *args, **kwargs)

map_intrinsic_literal(expr, *args, **kwargs)

map_int_literal(expr, *args, **kwargs)

map_float_literal(expr, *args, **kwargs)

map_variable_symbol(expr, *args, **kwargs)

map_deferred_type_symbol(expr, *args, **kwargs)

map_meta_symbol(expr, *args, **kwargs)

map_scalar(expr, *args, **kwargs)

map_array(expr, *args, **kwargs)

map_array_subscript(expr, *args, **kwargs)

map_string_subscript(expr, *args, **kwargs)

map_inline_call(expr, *args, **kwargs)

map_cast(expr, *args, **kwargs)

map_range(expr, *args, **kwargs)

map_range_index(expr, *args, **kwargs)

map_loop_range(expr, *args, **kwargs)

map_parenthesised_add(expr, *args, **kwargs)

map_parenthesised_mul(expr, *args, **kwargs)

map_parenthesised_div(expr, *args, **kwargs)

map_parenthesised_pow(expr, *args, **kwargs)

map_string_concat(expr, *args, **kwargs)

map_literal_list(expr, *args, **kwargs)

map_inline_do(expr, *args, **kwargs)

map_procedure_symbol(expr, *args, **kwargs)

class SubstituteExpressionsMapper(expr_map, invalidate_source=True)

Bases: LokiIdentityMapper

A Pymbolic expression mapper (i.e., a visitor for the expression tree) that defines on-the-fly handlers from a given substitution map.

It returns a copy of the expression tree with expressions substituted according to the given expr_map. If an expression node is encountered that is found in expr_map, it is replaced with the corresponding expression from the map. For any other nodes, traversal is performed via LokiIdentityMapper.

Note

No recursion is performed on substituted expression nodes, they are taken as-is from the map. Otherwise substitutions that involve the original node would result in infinite recursion - for example a replacement that wraps a variable in an inline call: my_var -> wrapped_in_call(my_var).

When there is a need to recursively apply the mapping, the mapping needs to be applied to itself first. A potential use-case is renaming of variables, which may appear as the name of an array subscript as well as in the dimensions attribute of the same expression: SOME_ARR(SOME_ARR > SOME_VAL). The mapping can be applied to itself using the utility function recursive_expression_map_update.

Parameters:

• expr_map (dict) – Expression mapping to apply to the expression tree.

• invalidate_source (bool, optional) – By default the source property of nodes is discarded when rebuilding the node, setting this to False allows to retain that information

map_from_expr_map(expr, *args, **kwargs)

Replace an expr with its substitution, if found in the expr_map, otherwise continue tree traversal

class LokiIdentityMapper(invalidate_source=True)

Bases: IdentityMapper

A visitor to traverse and transform an expression tree

This can serve as basis for any transformation mappers that apply changes to the expression tree. Expression nodes that are unchanged are returned as is.

Parameters:

invalidate_source (bool, optional) – By default the source property of nodes is discarded when rebuilding the node, setting this to False allows to retain that information

rec(expr, *args, **kwargs)

Dispatch expr to its corresponding mapper method. Pass on *args and **kwargs unmodified.

This method is intended as the top-level dispatch entry point and may be overridden by subclasses to present a different/more convenient interface. rec() on the other hand is intended as the recursive dispatch method to be used to recurse within mapper method implementations.

map_algebraic_leaf(expr, *args, **kwargs)

map_logic_literal(expr, *args, **kwargs)

map_string_literal(expr, *args, **kwargs)

map_intrinsic_literal(expr, *args, **kwargs)

map_int_literal(expr, *args, **kwargs)

map_float_literal(expr, *args, **kwargs)

map_variable_symbol(expr, *args, **kwargs)

map_deferred_type_symbol(expr, *args, **kwargs)

map_procedure_symbol(expr, *args, **kwargs)

map_meta_symbol(expr, *args, **kwargs)

map_scalar(expr, *args, **kwargs)

map_array(expr, *args, **kwargs)

map_array_subscript(expr, *args, **kwargs)

map_string_subscript(expr, *args, **kwargs)

map_inline_call(expr, *args, **kwargs)

map_cast(expr, *args, **kwargs)

map_sum(expr, *args, **kwargs)

map_quotient(expr, *args, **kwargs)

map_parenthesised_add(expr, *args, **kwargs)

map_product(expr, *args, **kwargs)

map_parenthesised_mul(expr, *args, **kwargs)

map_parenthesised_div(expr, *args, **kwargs)

map_parenthesised_pow(expr, *args, **kwargs)

map_string_concat(expr, *args, **kwargs)

map_range(expr, *args, **kwargs)

map_range_index(expr, *args, **kwargs)

map_loop_range(expr, *args, **kwargs)

map_literal_list(expr, *args, **kwargs)

map_inline_do(expr, *args, **kwargs)

map_c_reference(expr, *args, **kwargs)

map_c_dereference(expr, *args, **kwargs)

class AttachScopesMapper(fail=False)

Bases: LokiIdentityMapper

A Pymbolic expression mapper (i.e., a visitor for the expression tree) that determines the scope of TypedSymbol nodes and updates its scope pointer accordingly.

Parameters:

fail (bool, optional) – If True, the mapper raises RuntimeError if the scope for a symbol can not be found.

map_variable_symbol(expr, *args, **kwargs)

Handler for VariableSymbol

This updates the symbol’s scope via _update_symbol_scope() and then calls the parent class handler routine

Note: this may be a different handler as attaching the scope and therefore type may change a symbol’s type, e.g. from DeferredTypeSymbol to Scalar

map_deferred_type_symbol(expr, *args, **kwargs)

Handler for VariableSymbol

This updates the symbol’s scope via _update_symbol_scope() and then calls the parent class handler routine

Note: this may be a different handler as attaching the scope and therefore type may change a symbol’s type, e.g. from DeferredTypeSymbol to Scalar

map_procedure_symbol(expr, *args, **kwargs)

Handler for VariableSymbol

This updates the symbol’s scope via _update_symbol_scope() and then calls the parent class handler routine

Note: this may be a different handler as attaching the scope and therefore type may change a symbol’s type, e.g. from DeferredTypeSymbol to Scalar

class DetachScopesMapper

Bases: LokiIdentityMapper

A Pymbolic expression mapper (i.e., a visitor for the expression tree) that rebuilds an expression unchanged but with the scope for every TypedSymbol detached.

This will ensure that type information is stored locally on the object itself, which is useful when storing information for inter-procedural analysis passes.

map_variable_symbol(expr, *args, **kwargs)

map_deferred_type_symbol(expr, *args, **kwargs)

map_procedure_symbol(expr, *args, **kwargs)