cerl - Core Erlang abstract syntax trees.
Please see following description for synopsis
cerl(3) Erlang Module Definition cerl(3)
NAME
cerl - Core Erlang abstract syntax trees.
DESCRIPTION
Core Erlang abstract syntax trees.
This module defines an abstract data type for representing Core Erlang
source code as syntax trees.
A recommended starting point for the first-time user is the documenta-
tion of the function type/1.
NOTES:
This module deals with the composition and decomposition of syntactic
entities (as opposed to semantic ones); its purpose is to hide all
direct references to the data structures used to represent these enti-
ties. With few exceptions, the functions in this module perform no
semantic interpretation of their inputs, and in general, the user is
assumed to pass type-correct arguments - if this is not done, the
effects are not defined.
Currently, the internal data structure used is the same as the record-
based data structures used traditionally in the Beam compiler.
The internal representations of abstract syntax trees are subject to
change without notice, and should not be documented outside this mod-
ule. Furthermore, we do not give any guarantees on how an abstract syn-
tax tree may or may not be represented, with the following exceptions:
no syntax tree is represented by a single atom, such as none, by a list
constructor [X | Y], or by the empty list []. This can be relied on
when writing functions that operate on syntax trees.
DATA TYPES
c_alias() = #c_alias{}:
c_apply() = #c_apply{}:
c_binary() = #c_binary{}:
c_bitstr() = #c_bitstr{}:
c_call() = #c_call{}:
c_case() = #c_case{}:
c_catch() = #c_catch{}:
c_clause() = #c_clause{}:
c_cons() = #c_cons{}:
c_fun() = #c_fun{}:
c_lct() = c_literal() | c_cons() | c_tuple():
c_let() = #c_let{}:
c_letrec() = #c_letrec{}:
c_literal() = #c_literal{}:
c_map() = #c_map{}:
c_map_pair() = #c_map_pair{}:
c_module() = #c_module{}:
c_primop() = #c_primop{}:
c_receive() = #c_receive{}:
c_seq() = #c_seq{}:
c_try() = #c_try{}:
c_tuple() = #c_tuple{}:
c_values() = #c_values{}:
c_var() = #c_var{}:
cerl() = c_alias() | c_apply() | c_binary() | c_bitstr() | c_call() |
c_case() | c_catch() | c_clause() | c_cons() | c_fun() | c_let() |
c_letrec() | c_literal() | c_map() | c_map_pair() | c_module() |
c_primop() | c_receive() | c_seq() | c_try() | c_tuple() | c_values()
| c_var():
ctype() = alias | apply | binary | bitstr | call | case | catch |
clause | cons | fun | let | letrec | literal | map | map_pair | mod-
ule | primop | receive | seq | try | tuple | values | var:
dtype() = cons | tuple | {atomic, value()}:
map_op() = #c_literal{val=assoc} | #c_literal{val=exact}:
value() = integer() | float() | atom() | []:
var_name() = integer() | atom() | {atom(), integer()}:
EXPORTS
abstract(T::term()) -> c_literal()
Creates a syntax tree corresponding to an Erlang term. Term must
be a literal term, i.e., one that can be represented as a source
code literal. Thus, it may not contain a process identifier,
port, reference, binary or function value as a subterm.
Note: This is a constant time operation.
See also: ann_abstract/2, concrete/1, is_literal/1, is_lit-
eral_term/1.
add_ann(Terms::[term()], Node::cerl()) -> cerl()
Appends Annotations to the list of user annotations of Node.
Note: this is equivalent to set_ann(Node, Annotations ++
get_ann(Node)), but potentially more efficient.
See also: get_ann/1, set_ann/2.
alias_pat(Node::c_alias()) -> cerl()
Returns the pattern subtree of an abstract pattern alias.
See also: c_alias/2.
alias_var(Node::c_alias()) -> c_var()
Returns the variable subtree of an abstract pattern alias.
See also: c_alias/2.
ann_abstract(As::[term()], T::term()) -> c_literal()
See also: abstract/1.
ann_c_alias(As::[term()], Var::c_var(), Pattern::cerl()) -> c_alias()
See also: c_alias/2.
ann_c_apply(As::[term()], Operator::cerl(), Arguments::[cerl()]) ->
c_apply()
See also: c_apply/2.
ann_c_atom(As::[term()], Name::atom() | string()) -> c_literal()
See also: c_atom/1.
ann_c_binary(As::[term()], Segments::[cerl()]) -> c_binary()
See also: c_binary/1.
ann_c_bitstr(As::[term()], Value::cerl(), Size::cerl(), Type::cerl(),
Flags::cerl()) -> c_bitstr()
Equivalent to ann_c_bitstr(As, Value, Size, abstract(1), Type,
Flags).
ann_c_bitstr(As::[term()], Val::cerl(), Size::cerl(), Unit::cerl(),
Type::cerl(), Flags::cerl()) -> c_bitstr()
See also: ann_c_bitstr/5, c_bitstr/5.
ann_c_call(As::[term()], Module::cerl(), Name::cerl(), Argu-
ments::[cerl()]) -> c_call()
See also: c_call/3.
ann_c_case(As::[term()], Expr::cerl(), Clauses::[cerl()]) -> c_case()
See also: c_case/2.
ann_c_catch(As::[term()], Body::cerl()) -> c_catch()
See also: c_catch/1.
ann_c_char(As::[term()], Value::char()) -> c_literal()
See also: c_char/1.
ann_c_clause(As::[term()], Patterns::[cerl()], Body::cerl()) ->
c_clause()
Equivalent to ann_c_clause(As, Patterns, c_atom(true), Body).
See also: c_clause/3.
ann_c_clause(As::[term()], Patterns::[cerl()], Guard::cerl(),
Body::cerl()) -> c_clause()
See also: ann_c_clause/3, c_clause/3.
ann_c_cons(As::[term()], C_literal::cerl(), Tail::cerl()) -> c_lit-
eral() | c_cons()
See also: c_cons/2.
ann_c_cons_skel(As::[term()], Head::cerl(), Tail::cerl()) -> c_cons()
See also: c_cons_skel/2.
ann_c_float(As::[term()], Value::float()) -> c_literal()
See also: c_float/1.
ann_c_fname(As::[term()], Atom::atom(), Arity::arity()) -> c_var()
Equivalent to ann_c_var(As, {Atom, Arity}).
See also: c_fname/2.
ann_c_fun(As::[term()], Variables::[cerl()], Body::cerl()) -> c_fun()
See also: c_fun/2.
ann_c_int(As::[term()], Value::integer()) -> c_literal()
See also: c_int/1.
ann_c_let(As::[term()], Variables::[cerl()], Argument::cerl(),
Body::cerl()) -> c_let()
See also: c_let/3.
ann_c_letrec(As::[term()], Defs::[{cerl(), cerl()}], Body::cerl()) ->
c_letrec()
See also: c_letrec/2.
ann_c_map(As::[term()], Es::[c_map_pair()]) -> c_map() | c_literal()
ann_c_map(As::[term()], C_literal::c_map() | c_literal(),
Es::[c_map_pair()]) -> c_map() | c_literal()
ann_c_map_pair(As::[term()], Op::cerl(), K::cerl(), V::cerl()) ->
c_map_pair()
ann_c_map_pattern(As::[term()], Pairs::[c_map_pair()]) -> c_map()
ann_c_module(As::[term()], Name::cerl(), Exports::[cerl()],
Es::[{cerl(), cerl()}]) -> c_module()
See also: ann_c_module/5, c_module/3.
ann_c_module(As::[term()], Name::cerl(), Exports::[cerl()],
Attrs::[{cerl(), cerl()}], Es::[{cerl(), cerl()}]) -> c_module()
See also: ann_c_module/4, c_module/4.
ann_c_nil(As::[term()]) -> c_literal()
See also: c_nil/0.
ann_c_primop(As::[term()], Name::cerl(), Arguments::[cerl()]) -> c_pri-
mop()
See also: c_primop/2.
ann_c_receive(As::[term()], Clauses::[cerl()]) -> c_receive()
Equivalent to ann_c_receive(As, Clauses, c_atom(infinity),
c_atom(true)).
See also: c_atom/1, c_receive/3.
ann_c_receive(As::[term()], Clauses::[cerl()], Timeout::cerl(),
Action::cerl()) -> c_receive()
See also: ann_c_receive/2, c_receive/3.
ann_c_seq(As::[term()], Argument::cerl(), Body::cerl()) -> c_seq()
See also: c_seq/2.
ann_c_string(As::[term()], Value::string()) -> c_literal()
See also: c_string/1.
ann_c_try(As::[term()], Expr::cerl(), Vs::[cerl()], Body::cerl(),
Evs::[cerl()], Handler::cerl()) -> c_try()
See also: c_try/5.
ann_c_tuple(As::[term()], Es::[cerl()]) -> c_tuple() | c_literal()
See also: c_tuple/1.
ann_c_tuple_skel(As::[term()], Es::[cerl()]) -> c_tuple()
See also: c_tuple_skel/1.
ann_c_values(As::[term()], Es::[cerl()]) -> c_values()
See also: c_values/1.
ann_c_var(As::[term()], Name::var_name()) -> c_var()
See also: c_var/1.
ann_make_data(As::[term()], X2::dtype(), Es::[cerl()]) -> c_lct()
See also: make_data/2.
ann_make_data_skel(As::[term()], X2::dtype(), Es::[cerl()]) -> c_lct()
See also: make_data_skel/2.
ann_make_list(As::[term()], List::[cerl()]) -> cerl()
Equivalent to ann_make_list(As, List, none).
ann_make_list(As::[term()], T::[cerl()], Tail::cerl() | none) -> cerl()
See also: ann_make_list/2, make_list/2.
ann_make_tree(As::[term()], X2::ctype(), X3::[[cerl()], ...]) -> cerl()
Creates a syntax tree with the given annotations, type and sub-
trees. See make_tree/2 for details.
See also: make_tree/2.
apply_args(Node::c_apply()) -> [cerl()]
Returns the list of argument subtrees of an abstract function
application.
See also: apply_arity/1, c_apply/2.
apply_arity(Node::c_apply()) -> arity()
Returns the number of argument subtrees of an abstract function
application.
Note: this is equivalent to length(apply_args(Node)), but poten-
tially more efficient.
See also: apply_args/1, c_apply/2.
apply_op(Node::c_apply()) -> cerl()
Returns the operator subtree of an abstract function applica-
tion.
See also: c_apply/2.
atom_lit(Node::cerl()) -> nonempty_string()
Returns the literal string represented by an abstract atom. This
always includes surrounding single-quote characters.
Note that an abstract atom may have several literal representa-
tions, and that the representation yielded by this function is
not fixed; e.g., atom_lit(c_atom("a\012b")) could yield the
string "\'a\\nb\'".
See also: c_atom/1.
atom_name(Node::c_literal()) -> string()
Returns the printname of an abstract atom.
See also: c_atom/1.
atom_val(Node::c_literal()) -> atom()
Returns the value represented by an abstract atom.
See also: c_atom/1.
binary_segments(Node::c_binary()) -> [cerl()]
Returns the list of segment subtrees of an abstract binary-tem-
plate.
See also: c_binary/1, c_bitstr/5.
bitstr_bitsize(Node::c_bitstr()) -> all | any | utf | non_neg_integer()
Returns the total size in bits of an abstract bit-string tem-
plate. If the size field is an integer literal, the result is
the product of the size and unit values; if the size field is
the atom literal all, the atom all is returned. If the size is
not a literal, the atom any is returned.
See also: c_bitstr/5.
bitstr_flags(Node::c_bitstr()) -> cerl()
Returns the flags subtree of an abstract bit-string template.
See also: c_bitstr/5.
bitstr_size(Node::c_bitstr()) -> cerl()
Returns the size subtree of an abstract bit-string template.
See also: c_bitstr/5.
bitstr_type(Node::c_bitstr()) -> cerl()
Returns the type subtree of an abstract bit-string template.
See also: c_bitstr/5.
bitstr_unit(Node::c_bitstr()) -> cerl()
Returns the unit subtree of an abstract bit-string template.
See also: c_bitstr/5.
bitstr_val(Node::c_bitstr()) -> cerl()
Returns the value subtree of an abstract bit-string template.
See also: c_bitstr/5.
c_alias(Var::c_var(), Pattern::cerl()) -> c_alias()
Creates an abstract pattern alias. The result represents "Vari-
able = Pattern".
See also: alias_pat/1, alias_var/1, ann_c_alias/3, c_clause/3,
is_c_alias/1, update_c_alias/3.
c_apply(Operator::cerl(), Arguments::[cerl()]) -> c_apply()
Creates an abstract function application. If Arguments is [A1,
..., An], the result represents "apply Operator(A1, ..., An)".
See also: ann_c_apply/3, apply_args/1, apply_arity/1,
apply_op/1, c_call/3, c_primop/2, is_c_apply/1,
update_c_apply/3.
c_atom(Name::atom() | string()) -> c_literal()
Creates an abstract atom literal. The print name of the atom is
the character sequence represented by Name.
Note: passing a string as argument to this function causes a
corresponding atom to be created for the internal representa-
tion.
See also: ann_c_atom/2, atom_lit/1, atom_name/1, atom_val/1,
is_c_atom/1.
c_binary(Segments::[cerl()]) -> c_binary()
Creates an abstract binary-template. A binary object is in this
context a sequence of an arbitrary number of bits. (The number
of bits used to be evenly divisible by 8, but after the intro-
duction of bit strings in the Erlang language, the choice was
made to use the binary template for all bit strings.) It is
specified by zero or more bit-string template segments of arbi-
trary lengths (in number of bits). If Segments is [S1, ..., Sn],
the result represents "#{S1, ..., Sn}#". All the Si must have
type bitstr.
See also: ann_c_binary/2, binary_segments/1, c_bitstr/5,
is_c_binary/1, update_c_binary/2.
c_bitstr(Val::cerl(), Type::cerl(), Flags::cerl()) -> c_bitstr()
Equivalent to c_bitstr(Value, abstract(all), abstract(1), Type,
Flags).
c_bitstr(Val::cerl(), Size::cerl(), Type::cerl(), Flags::cerl()) ->
c_bitstr()
Equivalent to c_bitstr(Value, Size, abstract(1), Type, Flags).
c_bitstr(Val::cerl(), Size::cerl(), Unit::cerl(), Type::cerl(),
Flags::cerl()) -> c_bitstr()
Creates an abstract bit-string template. These can only occur as
components of an abstract binary-template (see c_binary/1). The
result represents "#<Value>(Size, Unit, Type, Flags)", where
Unit must represent a positive integer constant, Type must rep-
resent a constant atom (one of 'integer', 'float', or 'binary'),
and Flags must represent a constant list "[F1, ..., Fn]" where
all the Fi are atoms.
See also: ann_c_bitstr/6, bitstr_flags/1, bitstr_size/1, bit-
str_type/1, bitstr_unit/1, bitstr_val/1, c_binary/1, is_c_bit-
str/1, update_c_bitstr/6.
c_call(Module::cerl(), Name::cerl(), Arguments::[cerl()]) -> c_call()
Creates an abstract inter-module call. If Arguments is [A1, ...,
An], the result represents "call Module:Name(A1, ..., An)".
See also: ann_c_call/4, c_apply/2, c_primop/2, call_args/1,
call_arity/1, call_module/1, call_name/1, is_c_call/1,
update_c_call/4.
c_case(Expr::cerl(), Clauses::[cerl()]) -> c_case()
Creates an abstract case-expression. If Clauses is [C1, ...,
Cn], the result represents "case Argument of C1 ... Cn end".
Clauses must not be empty.
See also: ann_c_case/3, c_clause/3, case_arg/1, case_arity/1,
case_clauses/1, is_c_case/1, update_c_case/3.
c_catch(Body::cerl()) -> c_catch()
Creates an abstract catch-expression. The result represents
"catch Body".
Note: catch-expressions can be rewritten as try-expressions, and
will eventually be removed from Core Erlang.
See also: ann_c_catch/2, c_try/5, catch_body/1, is_c_catch/1,
update_c_catch/2.
c_char(Value::non_neg_integer()) -> c_literal()
Creates an abstract character literal. If the local implementa-
tion of Erlang defines char() as a subset of integer(), this
function is equivalent to c_int/1. Otherwise, if the given value
is an integer, it will be converted to the character with the
corresponding code. The lexical representation of a character is
"$Char", where Char is a single printing character or an escape
sequence.
See also: ann_c_char/2, c_int/1, c_string/1, char_lit/1,
char_val/1, is_c_char/1, is_print_char/1.
c_clause(Patterns::[cerl()], Body::cerl()) -> c_clause()
Equivalent to c_clause(Patterns, c_atom(true), Body).
See also: c_atom/1.
c_clause(Patterns::[cerl()], Guard::cerl(), Body::cerl()) -> c_clause()
Creates an an abstract clause. If Patterns is [P1, ..., Pn], the
result represents "<P1, ..., Pn> when Guard -> Body".
See also: ann_c_clause/4, c_case/2, c_clause/2, c_receive/3,
clause_arity/1, clause_body/1, clause_guard/1, clause_pats/1,
clause_vars/1, is_c_clause/1, update_c_clause/4.
c_cons(C_literal::cerl(), Tail::cerl()) -> c_literal() | c_cons()
Creates an abstract list constructor. The result represents
"[Head | Tail]". Note that if both Head and Tail have type lit-
eral, then the result will also have type literal, and annota-
tions on Head and Tail are lost.
Recall that in Erlang, the tail element of a list constructor is
not necessarily a list.
See also: ann_c_cons/3, c_cons_skel/2, c_nil/0, cons_hd/1,
cons_tl/1, is_c_cons/1, is_c_list/1, list_elements/1,
list_length/1, make_list/2, update_c_cons/3.
c_cons_skel(Head::cerl(), Tail::cerl()) -> c_cons()
Creates an abstract list constructor skeleton. Does not fold
constant literals, i.e., the result always has type cons, repre-
senting "[Head | Tail]".
This function is occasionally useful when it is necessary to
have annotations on the subnodes of a list constructor node,
even when the subnodes are constant literals. Note however that
is_literal/1 will yield false and concrete/1 will fail if passed
the result from this function.
fold_literal/1 can be used to revert a node to the normal-form
representation.
See also: ann_c_cons_skel/3, c_cons/2, c_nil/0, concrete/1,
fold_literal/1, is_c_cons/1, is_c_list/1, is_literal/1,
update_c_cons_skel/3.
c_float(Value::float()) -> c_literal()
Creates an abstract floating-point literal. The lexical repre-
sentation is the decimal floating-point numeral of Value.
See also: ann_c_float/2, float_lit/1, float_val/1, is_c_float/1.
c_fname(Atom::atom(), Arity::arity()) -> c_var()
Equivalent to c_var({Name, Arity}).
See also: ann_c_fname/3, fname_arity/1, fname_id/1,
is_c_fname/1, update_c_fname/3.
c_fun(Variables::[cerl()], Body::cerl()) -> c_fun()
Creates an abstract fun-expression. If Variables is [V1, ...,
Vn], the result represents "fun (V1, ..., Vn) -> Body". All the
Vi must have type var.
See also: ann_c_fun/3, fun_arity/1, fun_body/1, fun_vars/1,
is_c_fun/1, update_c_fun/3.
c_int(Value::integer()) -> c_literal()
Creates an abstract integer literal. The lexical representation
is the canonical decimal numeral of Value.
See also: ann_c_int/2, c_char/1, int_lit/1, int_val/1,
is_c_int/1.
c_let(Variables::[cerl()], Argument::cerl(), Body::cerl()) -> c_let()
Creates an abstract let-expression. If Variables is [V1, ...,
Vn], the result represents "let <V1, ..., Vn> = Argument in
Body". All the Vi must have type var.
See also: ann_c_let/4, is_c_let/1, let_arg/1, let_arity/1,
let_body/1, let_vars/1, update_c_let/4.
c_letrec(Defs::[{cerl(), cerl()}], Body::cerl()) -> c_letrec()
Creates an abstract letrec-expression. If Definitions is [{V1,
F1}, ..., {Vn, Fn}], the result represents "letrec V1 = F1 ...
Vn = Fn in Body. All the Vi must have type var and represent
function names. All the Fi must have type 'fun'.
See also: ann_c_letrec/3, is_c_letrec/1, letrec_body/1,
letrec_defs/1, letrec_vars/1, update_c_letrec/3.
c_map(Pairs::[c_map_pair()]) -> c_map()
c_map_pair(Key::cerl(), Val::cerl()) -> c_map_pair()
c_map_pair_exact(Key::cerl(), Val::cerl()) -> c_map_pair()
c_map_pattern(Pairs::[c_map_pair()]) -> c_map()
c_module(Name::cerl(), Exports::[cerl()], Es::[{cerl(), cerl()}]) ->
c_module()
Equivalent to c_module(Name, Exports, [], Definitions).
c_module(Name::cerl(), Exports::[cerl()], Attrs::[{cerl(), cerl()}],
Es::[{cerl(), cerl()}]) -> c_module()
Creates an abstract module definition. The result represents
module Name [E1, ..., Ek]
attributes [K1 = T1, ...,
Km = Tm]
V1 = F1
...
Vn = Fn
end
if Exports = [E1, ..., Ek], Attributes = [{K1, T1}, ..., {Km,
Tm}], and Definitions = [{V1, F1}, ..., {Vn, Fn}].
Name and all the Ki must be atom literals, and all the Ti must
be constant literals. All the Vi and Ei must have type var and
represent function names. All the Fi must have type 'fun'.
See also: ann_c_module/4, ann_c_module/5, c_atom/1, c_fun/2,
c_module/3, c_var/1, is_literal/1, module_attrs/1, mod-
ule_defs/1, module_exports/1, module_name/1, module_vars/1,
update_c_module/5.
c_nil() -> c_literal()
Creates an abstract empty list. The result represents "[]". The
empty list is traditionally called "nil".
See also: ann_c_nil/1, c_cons/2, is_c_list/1.
c_primop(Name::cerl(), Arguments::[cerl()]) -> c_primop()
Creates an abstract primitive operation call. If Arguments is
[A1, ..., An], the result represents "primop Name(A1, ..., An)".
Name must be an atom literal.
See also: ann_c_primop/3, c_apply/2, c_call/3, is_c_primop/1,
primop_args/1, primop_arity/1, primop_name/1, update_c_primop/3.
c_receive(Clauses::[cerl()]) -> c_receive()
Equivalent to c_receive(Clauses, c_atom(infinity),
c_atom(true)).
See also: c_atom/1.
c_receive(Clauses::[cerl()], Timeout::cerl(), Action::cerl()) ->
c_receive()
Creates an abstract receive-expression. If Clauses is [C1, ...,
Cn], the result represents "receive C1 ... Cn after Timeout ->
Action end".
See also: ann_c_receive/4, c_receive/1, is_c_receive/1,
receive_action/1, receive_clauses/1, receive_timeout/1,
update_c_receive/4.
c_seq(Argument::cerl(), Body::cerl()) -> c_seq()
Creates an abstract sequencing expression. The result represents
"do Argument Body".
See also: ann_c_seq/3, is_c_seq/1, seq_arg/1, seq_body/1,
update_c_seq/3.
c_string(Value::string()) -> c_literal()
Creates an abstract string literal. Equivalent to creating an
abstract list of the corresponding character literals (cf.
is_c_string/1), but is typically more efficient. The lexical
representation of a string is ""Chars"", where Chars is a
sequence of printing characters or spaces.
See also: ann_c_string/2, c_char/1, is_c_string/1,
is_print_string/1, string_lit/1, string_val/1.
c_try(Expr::cerl(), Vs::[cerl()], Body::cerl(), Evs::[cerl()], Han-
dler::cerl()) -> c_try()
Creates an abstract try-expression. If Variables is [V1, ...,
Vn] and ExceptionVars is [X1, ..., Xm], the result represents
"try Argument of <V1, ..., Vn> -> Body catch <X1, ..., Xm> ->
Handler". All the Vi and Xi must have type var.
See also: ann_c_try/6, c_catch/1, is_c_try/1, try_arg/1,
try_body/1, try_vars/1, update_c_try/6.
c_tuple(Es::[cerl()]) -> c_tuple() | c_literal()
Creates an abstract tuple. If Elements is [E1, ..., En], the
result represents "{E1, ..., En}". Note that if all nodes in
Elements have type literal, or if Elements is empty, then the
result will also have type literal and annotations on nodes in
Elements are lost.
Recall that Erlang has distinct 1-tuples, i.e., {X} is always
distinct from X itself.
See also: ann_c_tuple/2, c_tuple_skel/1, is_c_tuple/1,
tuple_arity/1, tuple_es/1, update_c_tuple/2.
c_tuple_skel(Es::[cerl()]) -> c_tuple()
Creates an abstract tuple skeleton. Does not fold constant lit-
erals, i.e., the result always has type tuple, representing
"{E1, ..., En}", if Elements is [E1, ..., En].
This function is occasionally useful when it is necessary to
have annotations on the subnodes of a tuple node, even when all
the subnodes are constant literals. Note however that is_lit-
eral/1 will yield false and concrete/1 will fail if passed the
result from this function.
fold_literal/1 can be used to revert a node to the normal-form
representation.
See also: ann_c_tuple_skel/2, c_tuple/1, concrete/1, fold_lit-
eral/1, is_c_tuple/1, is_literal/1, tuple_es/1,
update_c_tuple_skel/2.
c_values(Es::[cerl()]) -> c_values()
Creates an abstract value list. If Elements is [E1, ..., En],
the result represents "<E1, ..., En>".
See also: ann_c_values/2, is_c_values/1, update_c_values/2, val-
ues_arity/1, values_es/1.
c_var(Name::var_name()) -> c_var()
Creates an abstract variable. A variable is identified by its
name, given by the Name parameter.
If a name is given by a single atom, it should either be a "sim-
ple" atom which does not need to be single-quoted in Erlang, or
otherwise its print name should correspond to a proper Erlang
variable, i.e., begin with an uppercase character or an under-
score. Names on the form {A, N} represent function name vari-
ables "A/N"; these are special variables which may be bound only
in the function definitions of a module or a letrec. They may
not be bound in let expressions and cannot occur in clause pat-
terns. The atom A in a function name may be any atom; the inte-
ger N must be nonnegative. The functions c_fname/2 etc. are
utilities for handling function name variables.
When printing variable names, they must have the form of proper
Core Erlang variables and function names. E.g., a name repre-
sented by an integer such as 42 could be formatted as "_42", an
atom 'Xxx' simply as "Xxx", and an atom foo as "_foo". However,
one must assure that any two valid distinct names are never
mapped to the same strings. Tuples such as {foo, 2} representing
function names can simply by formatted as "'foo'/2", with no
risk of conflicts.
See also: ann_c_var/2, c_fname/2, c_letrec/2, c_module/4,
is_c_var/1, update_c_var/2, var_name/1.
call_args(Node::c_call()) -> [cerl()]
Returns the list of argument subtrees of an abstract inter-mod-
ule call.
See also: c_call/3, call_arity/1.
call_arity(Node::c_call()) -> arity()
Returns the number of argument subtrees of an abstract inter-
module call.
Note: this is equivalent to length(call_args(Node)), but poten-
tially more efficient.
See also: c_call/3, call_args/1.
call_module(Node::c_call()) -> cerl()
Returns the module subtree of an abstract inter-module call.
See also: c_call/3.
call_name(Node::c_call()) -> cerl()
Returns the name subtree of an abstract inter-module call.
See also: c_call/3.
case_arg(Node::c_case()) -> cerl()
Returns the argument subtree of an abstract case-expression.
See also: c_case/2.
case_arity(Node::c_case()) -> non_neg_integer()
Equivalent to clause_arity(hd(case_clauses(Node))), but poten-
tially more efficient.
See also: c_case/2, case_clauses/1, clause_arity/1.
case_clauses(Node::c_case()) -> [cerl()]
Returns the list of clause subtrees of an abstract case-expres-
sion.
See also: c_case/2, case_arity/1.
catch_body(Node::c_catch()) -> cerl()
Returns the body subtree of an abstract catch-expression.
See also: c_catch/1.
char_lit(Node::c_literal()) -> nonempty_string()
Returns the literal string represented by an abstract character.
This includes a leading $ character. Currently, all characters
that are not in the set of ISO 8859-1 (Latin-1) "printing" char-
acters will be escaped.
See also: c_char/1.
char_val(Node::c_literal()) -> char()
Returns the value represented by an abstract character literal.
See also: c_char/1.
clause_arity(Node::c_clause()) -> non_neg_integer()
Returns the number of pattern subtrees of an abstract clause.
Note: this is equivalent to length(clause_pats(Node)), but
potentially more efficient.
See also: c_clause/3, clause_pats/1.
clause_body(Node::c_clause()) -> cerl()
Returns the body subtree of an abstract clause.
See also: c_clause/3.
clause_guard(Node::c_clause()) -> cerl()
Returns the guard subtree of an abstract clause.
See also: c_clause/3.
clause_pats(Node::c_clause()) -> [cerl()]
Returns the list of pattern subtrees of an abstract clause.
See also: c_clause/3, clause_arity/1.
clause_vars(Clause::c_clause()) -> [cerl()]
Returns the list of all abstract variables in the patterns of an
abstract clause. The order of listing is not defined.
See also: c_clause/3, pat_list_vars/1.
concrete(C_literal::c_literal()) -> term()
Returns the Erlang term represented by a syntax tree. An excep-
tion is thrown if Node does not represent a literal term.
Note: This is a constant time operation.
See also: abstract/1, is_literal/1.
cons_hd(C_cons::c_cons() | c_literal()) -> cerl()
Returns the head subtree of an abstract list constructor.
See also: c_cons/2.
cons_tl(C_cons::c_cons() | c_literal()) -> cerl()
Returns the tail subtree of an abstract list constructor.
Recall that the tail does not necessarily represent a proper
list.
See also: c_cons/2.
copy_ann(Source::cerl(), Target::cerl()) -> cerl()
Copies the list of user annotations from Source to Target.
Note: this is equivalent to set_ann(Target, get_ann(Source)),
but potentially more efficient.
See also: get_ann/1, set_ann/2.
data_arity(C_literal::c_lct()) -> non_neg_integer()
Returns the number of subtrees of a data constructor node. This
is equivalent to length(data_es(Node)), but potentially more
efficient.
See also: data_es/1, is_data/1.
data_es(C_literal::c_lct()) -> [cerl()]
Returns the list of subtrees of a data constructor node. If the
arity of the constructor is zero, the result is the empty list.
Note: if data_type(Node) is cons, the number of subtrees is
exactly two. If data_type(Node) is {atomic, Value}, the number
of subtrees is zero.
See also: data_arity/1, data_type/1, is_data/1, make_data/2.
data_type(C_literal::c_lct()) -> dtype()
Returns a type descriptor for a data constructor node. (Cf.
is_data/1.) This is mainly useful for comparing types and for
constructing new nodes of the same type (cf. make_data/2). If
Node represents an integer, floating-point number, atom or empty
list, the result is {atomic, Value}, where Value is the value of
concrete(Node), otherwise the result is either cons or tuple.
Type descriptors can be compared for equality or order (in the
Erlang term order), but remember that floating-point values
should in general never be tested for equality.
See also: concrete/1, is_data/1, make_data/2, type/1.
float_lit(Node::c_literal()) -> string()
Returns the numeral string represented by a floating-point lit-
eral node.
See also: c_float/1.
float_val(Node::c_literal()) -> float()
Returns the value represented by a floating-point literal node.
See also: c_float/1.
fname_arity(C_var::c_var()) -> arity()
Returns the arity part of an abstract function name variable.
See also: c_fname/2, fname_id/1.
fname_id(C_var::c_var()) -> atom()
Returns the identifier part of an abstract function name vari-
able.
See also: c_fname/2, fname_arity/1.
fold_literal(Node::cerl()) -> cerl()
Assures that literals have a compact representation. This is
occasionally useful if c_cons_skel/2, c_tuple_skel/1 or
unfold_literal/1 were used in the construction of Node, and you
want to revert to the normal "folded" representation of liter-
als. If Node represents a tuple or list constructor, its ele-
ments are rewritten recursively, and the node is reconstructed
using c_cons/2 or c_tuple/1, respectively; otherwise, Node is
not changed.
See also: c_cons/2, c_cons_skel/2, c_tuple/1, c_tuple_skel/1,
is_literal/1, unfold_literal/1.
from_records(Node::cerl()) -> cerl()
Translates an explicit record representation to a corresponding
abstract syntax tree. The records are defined in the file
"core_parse.hrl".
See also: to_records/1, type/1.
fun_arity(Node::c_fun()) -> arity()
Returns the number of parameter subtrees of an abstract fun-
expression.
Note: this is equivalent to length(fun_vars(Node)), but poten-
tially more efficient.
See also: c_fun/2, fun_vars/1.
fun_body(Node::c_fun()) -> cerl()
Returns the body subtree of an abstract fun-expression.
See also: c_fun/2.
fun_vars(Node::c_fun()) -> [cerl()]
Returns the list of parameter subtrees of an abstract fun-
expression.
See also: c_fun/2, fun_arity/1.
get_ann(Node::cerl()) -> [term()]
Returns the list of user annotations associated with a syntax
tree node. For a newly created node, this is the empty list. The
annotations may be any terms.
See also: set_ann/2.
int_lit(Node::c_literal()) -> string()
Returns the numeral string represented by an integer literal
node.
See also: c_int/1.
int_val(Node::c_literal()) -> integer()
Returns the value represented by an integer literal node.
See also: c_int/1.
is_c_alias(C_alias::cerl()) -> boolean()
Returns true if Node is an abstract pattern alias, otherwise
false.
See also: c_alias/2.
is_c_apply(C_apply::cerl()) -> boolean()
Returns true if Node is an abstract function application, other-
wise false.
See also: c_apply/2.
is_c_atom(C_literal::cerl()) -> boolean()
Returns true if Node represents an atom literal, otherwise
false.
See also: c_atom/1.
is_c_binary(C_binary::cerl()) -> boolean()
Returns true if Node is an abstract binary-template; otherwise
false.
See also: c_binary/1.
is_c_bitstr(C_bitstr::cerl()) -> boolean()
Returns true if Node is an abstract bit-string template; other-
wise false.
See also: c_bitstr/5.
is_c_call(C_call::cerl()) -> boolean()
Returns true if Node is an abstract inter-module call expres-
sion; otherwise false.
See also: c_call/3.
is_c_case(C_case::cerl()) -> boolean()
Returns true if Node is an abstract case-expression; otherwise
false.
See also: c_case/2.
is_c_catch(C_catch::cerl()) -> boolean()
Returns true if Node is an abstract catch-expression, otherwise
false.
See also: c_catch/1.
is_c_char(C_literal::c_literal()) -> boolean()
Returns true if Node may represent a character literal, other-
wise false.
If the local implementation of Erlang defines char() as a subset
of integer(), then is_c_int(Node) will also yield true.
See also: c_char/1, is_print_char/1.
is_c_clause(C_clause::cerl()) -> boolean()
Returns true if Node is an abstract clause, otherwise false.
See also: c_clause/3.
is_c_cons(C_cons::cerl()) -> boolean()
Returns true if Node is an abstract list constructor, otherwise
false.
is_c_float(C_literal::cerl()) -> boolean()
Returns true if Node represents a floating-point literal, other-
wise false.
See also: c_float/1.
is_c_fname(C_var::cerl()) -> boolean()
Returns true if Node is an abstract function name variable, oth-
erwise false.
See also: c_fname/2, c_var/1, var_name/1.
is_c_fun(C_fun::cerl()) -> boolean()
Returns true if Node is an abstract fun-expression, otherwise
false.
See also: c_fun/2.
is_c_int(C_literal::cerl()) -> boolean()
Returns true if Node represents an integer literal, otherwise
false.
See also: c_int/1.
is_c_let(C_let::cerl()) -> boolean()
Returns true if Node is an abstract let-expression, otherwise
false.
See also: c_let/3.
is_c_letrec(C_letrec::cerl()) -> boolean()
Returns true if Node is an abstract letrec-expression, otherwise
false.
See also: c_letrec/2.
is_c_list(C_cons::cerl()) -> boolean()
Returns true if Node represents a proper list, otherwise false.
A proper list is either the empty list [], or a cons cell [Head
| Tail], where recursively Tail is a proper list.
Note: Because Node is a syntax tree, the actual run-time values
corresponding to its subtrees may often be partially or com-
pletely unknown. Thus, if Node represents e.g. "[... | Ns]"
(where Ns is a variable), then the function will return false,
because it is not known whether Ns will be bound to a list at
run-time. If Node instead represents e.g. "[1, 2, 3]" or "[A |
[]]", then the function will return true.
See also: c_cons/2, c_nil/0, list_elements/1, list_length/1.
is_c_map(C_map::cerl()) -> boolean()
Returns true if Node is an abstract map constructor, otherwise
false.
is_c_map_empty(C_map::c_map() | c_literal()) -> boolean()
is_c_map_pattern(C_map::c_map()) -> boolean()
is_c_module(C_module::cerl()) -> boolean()
Returns true if Node is an abstract module definition, otherwise
false.
See also: type/1.
is_c_nil(C_literal::cerl()) -> boolean()
Returns true if Node is an abstract empty list, otherwise false.
is_c_primop(C_primop::cerl()) -> boolean()
Returns true if Node is an abstract primitive operation call,
otherwise false.
See also: c_primop/2.
is_c_receive(C_receive::cerl()) -> boolean()
Returns true if Node is an abstract receive-expression, other-
wise false.
See also: c_receive/3.
is_c_seq(C_seq::cerl()) -> boolean()
Returns true if Node is an abstract sequencing expression, oth-
erwise false.
See also: c_seq/2.
is_c_string(C_literal::cerl()) -> boolean()
Returns true if Node may represent a string literal, otherwise
false. Strings are defined as lists of characters; see
is_c_char/1 for details.
See also: c_string/1, is_c_char/1, is_print_string/1.
is_c_try(C_try::cerl()) -> boolean()
Returns true if Node is an abstract try-expression, otherwise
false.
See also: c_try/5.
is_c_tuple(C_tuple::cerl()) -> boolean()
Returns true if Node is an abstract tuple, otherwise false.
See also: c_tuple/1.
is_c_values(C_values::cerl()) -> boolean()
Returns true if Node is an abstract value list; otherwise false.
See also: c_values/1.
is_c_var(C_var::cerl()) -> boolean()
Returns true if Node is an abstract variable, otherwise false.
See also: c_var/1.
is_data(C_literal::cerl()) -> boolean()
Returns true if Node represents a data constructor, otherwise
false. Data constructors are cons cells, tuples, and atomic lit-
erals.
See also: data_arity/1, data_es/1, data_type/1.
is_leaf(Node::cerl()) -> boolean()
Returns true if Node is a leaf node, otherwise false. The cur-
rent leaf node types are literal and var.
Note: all literals (cf. is_literal/1) are leaf nodes, even if
they represent structured (constant) values such as {foo, [bar,
baz]}. Also note that variables are leaf nodes but not literals.
See also: is_literal/1, type/1.
is_literal(C_literal::cerl()) -> boolean()
Returns true if Node represents a literal term, otherwise false.
This function returns true if and only if the value of con-
crete(Node) is defined.
Note: This is a constant time operation.
See also: abstract/1, concrete/1, fold_literal/1.
is_literal_term(T::term()) -> boolean()
Returns true if Term can be represented as a literal, otherwise
false. This function takes time proportional to the size of
Term.
See also: abstract/1.
is_print_char(C_literal::cerl()) -> boolean()
Returns true if Node may represent a "printing" character, oth-
erwise false. (Cf. is_c_char/1.) A "printing" character has
either a given graphical representation, or a "named" escape
sequence such as "\n". Currently, only ISO 8859-1 (Latin-1)
character values are recognized.
See also: c_char/1, is_c_char/1.
is_print_string(C_literal::cerl()) -> boolean()
Returns true if Node may represent a string literal containing
only "printing" characters, otherwise false. See is_c_string/1
and is_print_char/1 for details. Currently, only ISO 8859-1
(Latin-1) character values are recognized.
See also: c_string/1, is_c_string/1, is_print_char/1.
let_arg(Node::c_let()) -> cerl()
Returns the argument subtree of an abstract let-expression.
See also: c_let/3.
let_arity(Node::c_let()) -> non_neg_integer()
Returns the number of left-hand side variables of an abstract
let-expression.
Note: this is equivalent to length(let_vars(Node)), but poten-
tially more efficient.
See also: c_let/3, let_vars/1.
let_body(Node::c_let()) -> cerl()
Returns the body subtree of an abstract let-expression.
See also: c_let/3.
let_vars(Node::c_let()) -> [cerl()]
Returns the list of left-hand side variables of an abstract let-
expression.
See also: c_let/3, let_arity/1.
letrec_body(Node::c_letrec()) -> cerl()
Returns the body subtree of an abstract letrec-expression.
See also: c_letrec/2.
letrec_defs(Node::c_letrec()) -> [{cerl(), cerl()}]
Returns the list of definitions of an abstract letrec-expres-
sion. If Node represents "letrec V1 = F1 ... Vn = Fn in Body",
the returned value is [{V1, F1}, ..., {Vn, Fn}].
See also: c_letrec/2.
letrec_vars(Node::c_letrec()) -> [cerl()]
Returns the list of left-hand side function variable subtrees of
a letrec-expression. If Node represents "letrec V1 = F1 ... Vn =
Fn in Body", the returned value is [V1, ..., Vn].
See also: c_letrec/2.
list_elements(C_cons::c_cons() | c_literal()) -> [cerl()]
Returns the list of element subtrees of an abstract list. Node
must represent a proper list. E.g., if Node represents "[X1, X2
| [X3, X4 | []]", then list_elements(Node) yields the list [X1,
X2, X3, X4].
See also: c_cons/2, c_nil/0, is_c_list/1, list_length/1,
make_list/2.
list_length(L::c_cons() | c_literal()) -> non_neg_integer()
Returns the number of element subtrees of an abstract list. Node
must represent a proper list. E.g., if Node represents "[X1 |
[X2, X3 | [X4, X5, X6]]]", then list_length(Node) returns the
integer 6.
Note: this is equivalent to length(list_elements(Node)), but
potentially more efficient.
See also: c_cons/2, c_nil/0, is_c_list/1, list_elements/1.
make_data(CType::dtype(), Es::[cerl()]) -> c_lct()
Creates a data constructor node with the specified type and sub-
trees. (Cf. data_type/1.) An exception is thrown if the length
of Elements is invalid for the given Type; see data_es/1 for
arity constraints on constructor types.
See also: ann_make_data/3, data_es/1, data_type/1,
make_data_skel/2, update_data/3.
make_data_skel(CType::dtype(), Es::[cerl()]) -> c_lct()
Like make_data/2, but analogous to c_tuple_skel/1 and
c_cons_skel/2.
See also: ann_make_data_skel/3, c_cons_skel/2, c_tuple_skel/1,
make_data/2, update_data_skel/3.
make_list(List::[cerl()]) -> cerl()
Equivalent to make_list(List, none).
make_list(List::[cerl()], Tail::cerl() | none) -> cerl()
Creates an abstract list from the elements in List and the
optional Tail. If Tail is none, the result will represent a nil-
terminated list, otherwise it represents "[... | Tail]".
See also: ann_make_list/3, c_cons/2, c_nil/0, list_elements/1,
update_list/3.
make_tree(Type::ctype(), Gs::[[cerl()], ...]) -> cerl()
Creates a syntax tree with the given type and subtrees. Type
must be a node type name (cf. type/1) that does not denote a
leaf node type (cf. is_leaf/1). Groups must be a nonempty list
of groups of syntax trees, representing the subtrees of a node
of the given type, in left-to-right order as they would occur in
the printed program text, grouped by category as done by sub-
trees/1.
The result of ann_make_tree(get_ann(Node), type(Node), sub-
trees(Node)) (cf. update_tree/2) represents the same source code
text as the original Node, assuming that subtrees(Node) yields a
nonempty list. However, it does not necessarily have the exact
same data representation as Node.
See also: ann_make_tree/3, is_leaf/1, subtrees/1, type/1,
update_tree/2.
map_arg(C_literal::c_map() | c_literal()) -> c_map() | c_literal()
map_es(C_literal::c_map() | c_literal()) -> [c_map_pair()]
map_pair_key(C_map_pair::c_map_pair()) -> cerl()
map_pair_op(C_map_pair::c_map_pair()) -> map_op()
map_pair_val(C_map_pair::c_map_pair()) -> cerl()
meta(Node::cerl()) -> cerl()
Creates a meta-representation of a syntax tree. The result rep-
resents an Erlang expression "MetaTree" which, if evaluated,
will yield a new syntax tree representing the same source code
text as Tree (although the actual data representation may be
different). The expression represented by MetaTree is implemen-
tation independent with regard to the data structures used by
the abstract syntax tree implementation.
Any node in Tree whose node type is var (cf. type/1), and whose
list of annotations (cf. get_ann/1) contains the atom meta_var,
will remain unchanged in the resulting tree, except that exactly
one occurrence of meta_var is removed from its annotation list.
The main use of the function meta/1 is to transform a data
structure Tree, which represents a piece of program code, into a
form that is representation independent when printed. E.g., sup-
pose Tree represents a variable named "V". Then (assuming a
function print/1 for printing syntax trees), evaluating
print(abstract(Tree)) - simply using abstract/1 to map the
actual data structure onto a syntax tree representation - would
output a string that might look something like "{var, ...,
'V'}", which is obviously dependent on the implementation of the
abstract syntax trees. This could e.g. be useful for caching a
syntax tree in a file. However, in some situations like in a
program generator generator (with two "generator"), it may be
unacceptable. Using print(meta(Tree)) instead would output a
representation independent syntax tree generating expression; in
the above case, something like "cerl:c_var('V')".
The implementation tries to generate compact code with respect
to literals and lists.
See also: abstract/1, get_ann/1, type/1.
module_attrs(Node::c_module()) -> [{cerl(), cerl()}]
Returns the list of pairs of attribute key/value subtrees of an
abstract module definition.
See also: c_module/4.
module_defs(Node::c_module()) -> [{cerl(), cerl()}]
Returns the list of function definitions of an abstract module
definition.
See also: c_module/4.
module_exports(Node::c_module()) -> [cerl()]
Returns the list of exports subtrees of an abstract module defi-
nition.
See also: c_module/4.
module_name(Node::c_module()) -> cerl()
Returns the name subtree of an abstract module definition.
See also: c_module/4.
module_vars(Node::c_module()) -> [cerl()]
Returns the list of left-hand side function variable subtrees of
an abstract module definition.
See also: c_module/4.
pat_list_vars(Ps::[cerl()]) -> [cerl()]
Returns the list of all abstract variables in the given pat-
terns. An exception is thrown if some element in Patterns does
not represent a well-formed Core Erlang clause pattern. The
order of listing is not defined.
See also: clause_vars/1, pat_vars/1.
pat_vars(Node::cerl()) -> [cerl()]
Returns the list of all abstract variables in a pattern. An
exception is thrown if Node does not represent a well-formed
Core Erlang clause pattern. The order of listing is not defined.
See also: clause_vars/1, pat_list_vars/1.
primop_args(Node::c_primop()) -> [cerl()]
Returns the list of argument subtrees of an abstract primitive
operation call.
See also: c_primop/2, primop_arity/1.
primop_arity(Node::c_primop()) -> arity()
Returns the number of argument subtrees of an abstract primitive
operation call.
Note: this is equivalent to length(primop_args(Node)), but
potentially more efficient.
See also: c_primop/2, primop_args/1.
primop_name(Node::c_primop()) -> cerl()
Returns the name subtree of an abstract primitive operation
call.
See also: c_primop/2.
receive_action(Node::c_receive()) -> cerl()
Returns the action subtree of an abstract receive-expression.
See also: c_receive/3.
receive_clauses(Node::c_receive()) -> [cerl()]
Returns the list of clause subtrees of an abstract receive-
expression.
See also: c_receive/3.
receive_timeout(Node::c_receive()) -> cerl()
Returns the timeout subtree of an abstract receive-expression.
See also: c_receive/3.
seq_arg(Node::c_seq()) -> cerl()
Returns the argument subtree of an abstract sequencing expres-
sion.
See also: c_seq/2.
seq_body(Node::c_seq()) -> cerl()
Returns the body subtree of an abstract sequencing expression.
See also: c_seq/2.
set_ann(Node::cerl(), List::[term()]) -> cerl()
Sets the list of user annotations of Node to Annotations.
See also: add_ann/2, copy_ann/2, get_ann/1.
string_lit(Node::c_literal()) -> nonempty_string()
Returns the literal string represented by an abstract string.
This includes surrounding double-quote characters "...". Cur-
rently, characters that are not in the set of ISO 8859-1
(Latin-1) "printing" characters will be escaped, except for spa-
ces.
See also: c_string/1.
string_val(Node::c_literal()) -> string()
Returns the value represented by an abstract string literal.
See also: c_string/1.
subtrees(T::cerl()) -> [[cerl()]]
Returns the grouped list of all subtrees of a node. If Node is a
leaf node (cf. is_leaf/1), this is the empty list, otherwise the
result is always a nonempty list, containing the lists of sub-
trees of Node, in left-to-right order as they occur in the
printed program text, and grouped by category. Often, each group
contains only a single subtree.
Depending on the type of Node, the size of some groups may be
variable (e.g., the group consisting of all the elements of a
tuple), while others always contain the same number of elements
- usually exactly one (e.g., the group containing the argument
expression of a case-expression). Note, however, that the exact
structure of the returned list (for a given node type) should in
general not be depended upon, since it might be subject to
change without notice.
The function subtrees/1 and the constructor functions
make_tree/2 and update_tree/2 can be a great help if one wants
to traverse a syntax tree, visiting all its subtrees, but treat
nodes of the tree in a uniform way in most or all cases. Using
these functions makes this simple, and also assures that your
code is not overly sensitive to extensions of the syntax tree
data type, because any node types not explicitly handled by your
code can be left to a default case.
For example:
postorder(F, Tree) ->
F(case subtrees(Tree) of
[] -> Tree;
List -> update_tree(Tree,
[[postorder(F, Subtree)
|| Subtree <- Group]
|| Group <- List])
end).
maps the function F on Tree and all its subtrees, doing a post-
order traversal of the syntax tree. (Note the use of
update_tree/2 to preserve annotations.) For a simple function
like:
f(Node) ->
case type(Node) of
atom -> atom("a_" ++ atom_name(Node));
_ -> Node
end.
the call postorder(fun f/1, Tree) will yield a new representa-
tion of Tree in which all atom names have been extended with the
prefix "a_", but nothing else (including annotations) has been
changed.
See also: is_leaf/1, make_tree/2, update_tree/2.
to_records(Node::cerl()) -> cerl()
Translates an abstract syntax tree to a corresponding explicit
record representation. The records are defined in the file
"cerl.hrl".
See also: from_records/1, type/1.
try_arg(Node::c_try()) -> cerl()
Returns the expression subtree of an abstract try-expression.
See also: c_try/5.
try_body(Node::c_try()) -> cerl()
Returns the success body subtree of an abstract try-expression.
See also: c_try/5.
try_evars(Node::c_try()) -> [cerl()]
Returns the list of exception variable subtrees of an abstract
try-expression.
See also: c_try/5.
try_handler(Node::c_try()) -> cerl()
Returns the exception body subtree of an abstract try-expres-
sion.
See also: c_try/5.
try_vars(Node::c_try()) -> [cerl()]
Returns the list of success variable subtrees of an abstract
try-expression.
See also: c_try/5.
tuple_arity(C_tuple::c_tuple() | c_literal()) -> non_neg_integer()
Returns the number of element subtrees of an abstract tuple.
Note: this is equivalent to length(tuple_es(Node)), but poten-
tially more efficient.
See also: c_tuple/1, tuple_es/1.
tuple_es(C_tuple::c_tuple() | c_literal()) -> [cerl()]
Returns the list of element subtrees of an abstract tuple.
See also: c_tuple/1.
type(C_alias::cerl()) -> ctype()
Returns the type tag of Node. Current node types are:
alias apply binary bitstr call case catch clause
cons fun let letrec literal map map_pair module
primop receive seq try tuple values var
Note: The name of the primary constructor function for a node
type is always the name of the type itself, prefixed by "c_";
recognizer predicates are correspondingly prefixed by "is_c_".
Furthermore, to simplify preservation of annotations (cf.
get_ann/1), there are analogous constructor functions prefixed
by "ann_c_" and "update_c_", for setting the annotation list of
the new node to either a specific value or to the annotations of
an existing node, respectively.
See also: abstract/1, c_alias/2, c_apply/2, c_binary/1, c_bit-
str/5, c_call/3, c_case/2, c_catch/1, c_clause/3, c_cons/2,
c_fun/2, c_let/3, c_letrec/2, c_module/3, c_primop/2,
c_receive/1, c_seq/2, c_try/5, c_tuple/1, c_values/1, c_var/1,
data_type/1, from_records/1, get_ann/1, meta/1, subtrees/1,
to_records/1.
unfold_literal(Node::cerl()) -> cerl()
Assures that literals have a fully expanded representation. If
Node represents a literal tuple or list constructor, its ele-
ments are rewritten recursively, and the node is reconstructed
using c_cons_skel/2 or c_tuple_skel/1, respectively; otherwise,
Node is not changed. The fold_literal/1 can be used to revert to
the normal compact representation.
See also: c_cons/2, c_cons_skel/2, c_tuple/1, c_tuple_skel/1,
fold_literal/1, is_literal/1.
update_c_alias(Node::c_alias(), Var::cerl(), Pattern::cerl()) ->
c_alias()
See also: c_alias/2.
update_c_apply(Node::c_apply(), Operator::cerl(), Arguments::[cerl()])
-> c_apply()
See also: c_apply/2.
update_c_binary(Node::c_binary(), Segments::[cerl()]) -> c_binary()
See also: c_binary/1.
update_c_bitstr(Node::c_bitstr(), Value::cerl(), Size::cerl(),
Type::cerl(), Flags::cerl()) -> c_bitstr()
Equivalent to update_c_bitstr(Node, Value, Size, abstract(1),
Type, Flags).
update_c_bitstr(Node::c_bitstr(), Val::cerl(), Size::cerl(),
Unit::cerl(), Type::cerl(), Flags::cerl()) -> c_bitstr()
See also: c_bitstr/5, update_c_bitstr/5.
update_c_call(Node::cerl(), Module::cerl(), Name::cerl(), Argu-
ments::[cerl()]) -> c_call()
See also: c_call/3.
update_c_case(Node::c_case(), Expr::cerl(), Clauses::[cerl()]) ->
c_case()
See also: c_case/2.
update_c_catch(Node::c_catch(), Body::cerl()) -> c_catch()
See also: c_catch/1.
update_c_clause(Node::c_clause(), Patterns::[cerl()], Guard::cerl(),
Body::cerl()) -> c_clause()
See also: c_clause/3.
update_c_cons(Node::c_literal() | c_cons(), C_literal::cerl(),
Tail::cerl()) -> c_literal() | c_cons()
See also: c_cons/2.
update_c_cons_skel(Node::c_cons() | c_literal(), Head::cerl(),
Tail::cerl()) -> c_cons()
See also: c_cons_skel/2.
update_c_fname(C_var::c_var(), Atom::atom()) -> c_var()
Like update_c_fname/3, but takes the arity from Node.
See also: c_fname/2, update_c_fname/3.
update_c_fname(Node::c_var(), Atom::atom(), Arity::arity()) -> c_var()
Equivalent to update_c_var(Old, {Atom, Arity}).
See also: c_fname/2, update_c_fname/2.
update_c_fun(Node::c_fun(), Variables::[cerl()], Body::cerl()) ->
c_fun()
See also: c_fun/2.
update_c_let(Node::c_let(), Variables::[cerl()], Argument::cerl(),
Body::cerl()) -> c_let()
See also: c_let/3.
update_c_letrec(Node::c_letrec(), Defs::[{cerl(), cerl()}],
Body::cerl()) -> c_letrec()
See also: c_letrec/2.
update_c_map(C_map::c_map(), M::cerl(), Es::[cerl()]) -> c_map() |
c_literal()
update_c_map_pair(Old::c_map_pair(), Op::map_op(), K::cerl(),
V::cerl()) -> c_map_pair()
update_c_module(Node::c_module(), Name::cerl(), Exports::[cerl()],
Attrs::[{cerl(), cerl()}], Es::[{cerl(), cerl()}]) -> c_module()
See also: c_module/4.
update_c_primop(Node::cerl(), Name::cerl(), Arguments::[cerl()]) ->
c_primop()
See also: c_primop/2.
update_c_receive(Node::c_receive(), Clauses::[cerl()], Timeout::cerl(),
Action::cerl()) -> c_receive()
See also: c_receive/3.
update_c_seq(Node::c_seq(), Argument::cerl(), Body::cerl()) -> c_seq()
See also: c_seq/2.
update_c_try(Node::c_try(), Expr::cerl(), Vs::[cerl()], Body::cerl(),
Evs::[cerl()], Handler::cerl()) -> c_try()
See also: c_try/5.
update_c_tuple(Node::c_tuple() | c_literal(), Es::[cerl()]) ->
c_tuple() | c_literal()
See also: c_tuple/1.
update_c_tuple_skel(Old::c_tuple(), Es::[cerl()]) -> c_tuple()
See also: c_tuple_skel/1.
update_c_values(Node::c_values(), Es::[cerl()]) -> c_values()
See also: c_values/1.
update_c_var(Node::c_var(), Name::var_name()) -> c_var()
See also: c_var/1.
update_data(Node::cerl(), CType::dtype(), Es::[cerl()]) -> c_lct()
See also: make_data/2.
update_data_skel(Node::cerl(), CType::dtype(), Es::[cerl()]) -> c_lct()
See also: make_data_skel/2.
update_list(Node::cerl(), List::[cerl()]) -> cerl()
Equivalent to update_list(Old, List, none).
update_list(Node::cerl(), List::[cerl()], Tail::cerl() | none) ->
cerl()
See also: make_list/2, update_list/2.
update_tree(Node::cerl(), Gs::[[cerl()], ...]) -> cerl()
Creates a syntax tree with the given subtrees, and the same type
and annotations as the Old node. This is equivalent to
ann_make_tree(get_ann(Node), type(Node), Groups), but poten-
tially more efficient.
See also: ann_make_tree/3, get_ann/1, type/1, update_tree/3.
update_tree(Node::cerl(), Type::ctype(), Gs::[[cerl()], ...]) -> cerl()
Creates a syntax tree with the given type and subtrees, and the
same annotations as the Old node. This is equivalent to
ann_make_tree(get_ann(Node), Type, Groups), but potentially more
efficient.
See also: ann_make_tree/3, get_ann/1, update_tree/2.
values_arity(Node::c_values()) -> non_neg_integer()
Returns the number of element subtrees of an abstract value
list.
Note: This is equivalent to length(values_es(Node)), but poten-
tially more efficient.
See also: c_values/1, values_es/1.
values_es(Node::c_values()) -> [cerl()]
Returns the list of element subtrees of an abstract value list.
See also: c_values/1, values_arity/1.
var_name(Node::c_var()) -> var_name()
Returns the name of an abstract variable.
See also: c_var/1.
AUTHORS
Richard Carlsson <carlsson.richard@gmail.com>
compiler 8.0.4 cerl(3)