1cerl_trees(3) Erlang Module Definition cerl_trees(3)
2
6 cerl_trees - Basic functions on Core Erlang abstract syntax trees.
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9 Basic functions on Core Erlang abstract syntax trees.
10 Syntax trees are defined in the module cerl.
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14 cerl() = cerl:cerl():
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18 depth(T::cerl:cerl()) -> non_neg_integer()
19 Returns the length of the longest path in the tree. A leaf node
21 has depth zero, the tree representing "{foo, bar}" has depth
22 one, etc.
23 fold(F::(cerl:cerl(), term()) -> term(), S::term(), T::cerl:cerl()) ->
25 term()
26 Does a fold operation over the nodes of the tree. The result is
28 the value of Function(X1, Function(X2, ... Function(Xn, Unit)
29 ... )), where X1, ..., Xn are the nodes of Tree in a post-order
30 traversal.
31 See also: mapfold/3.
33 free_variables(T::cerl:cerl()) -> [cerl:var_name()]
35 Like variables/1, but only includes variables that are free in
37 the tree.
38 See also: next_free_variable_name/1, variables/1.
40 get_label(T::cerl:cerl()) -> top | integer()
42 label(T::cerl:cerl()) -> {cerl:cerl(), integer()}
44 Equivalent to label(Tree, 0).
46 label(T::cerl:cerl(), N::integer()) -> {cerl:cerl(), integer()}
48 Labels each expression in the tree. A term {label, L} is pre‐
50 fixed to the annotation list of each expression node, where L is
51 a unique number for every node, except for variables (and func‐
52 tion name variables) which get the same label if they represent
53 the same variable. Constant literal nodes are not labeled.
54 The returned value is a tuple {NewTree, Max}, where NewTree is
56 the labeled tree and Max is 1 plus the largest label value used.
57 All previous annotation terms on the form {label, X} are
58 deleted.
59 The values of L used in the tree is a dense range from N to Max
61 - 1, where N =< Max =< N + size(Tree). Note that it is possible
62 that no labels are used at all, i.e., N = Max.
63 Note: All instances of free variables will be given distinct la‐
65 bels.
66 See also: label/1, size/1.
68 map(F::(cerl:cerl()) -> cerl:cerl(), T::cerl:cerl()) -> cerl:cerl()
70 Maps a function onto the nodes of a tree. This replaces each
72 node in the tree by the result of applying the given function on
73 the original node, bottom-up.
74 See also: mapfold/3.
76 mapfold(F::(cerl:cerl(), term()) -> {cerl:cerl(), term()}, S0::term(),
78 T::cerl:cerl()) -> {cerl:cerl(), term()}
79 Does a combined map/fold operation on the nodes of the tree.
81 This is similar to map/2, but also propagates a value from each
82 application of Function to the next, starting with the given
83 value Initial, while doing a post-order traversal of the tree,
84 much like fold/3.
85 This is the same as mapfold/4, with an identity function as the
87 pre-operation.
88 See also: fold/3, map/2, mapfold/4.
90 mapfold(Pre::(cerl:cerl(), term()) -> {cerl:cerl(), term()} | skip,
92 Post::(cerl:cerl(), term()) -> {cerl:cerl(), term()}, S00::term(),
93 T0::cerl:cerl()) -> {cerl:cerl(), term()}
94 Does a combined map/fold operation on the nodes of the tree. It
96 begins by calling Pre on the tree, using the Initial value. Pre
97 must either return a tree with an updated accumulator or the
98 atom skip.
99 If a tree is returned, this function deconstructs the top node
101 of the returned tree and recurses on the children, using the re‐
102 turned value as the new initial and carrying the returned values
103 from one call to the next. Finally it reassembles the top node
104 from the children, calls Post on it and returns the result.
105 If skip is returned, it returns the tree and accumulator as is.
107 next_free_variable_name(T::cerl:cerl()) -> integer()
109 Returns a integer variable name higher than any other integer
111 variable name in the syntax tree. An exception is thrown if Tree
112 does not represent a well-formed Core Erlang syntax tree.
113 See also: free_variables/1, variables/1.
115 size(T::cerl:cerl()) -> non_neg_integer()
117 Returns the number of nodes in Tree.
119 variables(T::cerl:cerl()) -> [cerl:var_name()]
121 Returns an ordered-set list of the names of all variables in the
123 syntax tree. (This includes function name variables.) An excep‐
124 tion is thrown if Tree does not represent a well-formed Core Er‐
125 lang syntax tree.
126 See also: free_variables/1, next_free_variable_name/1.
128
130 Richard Carlsson <carlsson.richard@gmail.com>
131 compiler 8.4.1 cerl_trees(3)