Class: Trie
- Inherits:
-
Object
- Object
- Trie
- Defined in:
- ext/trie/trie.c,
ext/trie/trie.c
Overview
A key-value data structure for string keys which is efficient memory usage and fast retrieval time.
Class Method Summary collapse
-
.read(filename_base) ⇒ Trie
Returns a new trie with data as read from disk.
Instance Method Summary collapse
-
#add(args) ⇒ Object
Add a key, or a key and value to the Trie.
-
#children(prefix) ⇒ Array
Finds all keys in the Trie beginning with the given prefix.
-
#children_with_values(key) ⇒ Array
Finds all keys with their respective values in the Trie beginning with the given prefix.
-
#delete(key) ⇒ Object
Delete a key from the Trie.
-
#get(key) ⇒ Object
Retrieves the value for a particular key (or nil) from the Trie.
-
#has_key?(key) ⇒ Boolean
Determines whether or not a key exists in the Trie.
-
#root ⇒ TrieNode
Returns a TrieNode representing the root of the Trie.
-
#save(filename_base) ⇒ true
Saves the trie data to two files, filename_base.da and filename_base.tail.
Class Method Details
.read(filename_base) ⇒ Trie
Returns a new trie with data as read from disk.
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# File 'ext/trie/trie.c', line 33
static VALUE rb_trie_read(VALUE self, VALUE filename_base) {
VALUE da_filename = rb_str_dup(filename_base);
rb_str_concat(da_filename, rb_str_new2(".da"));
StringValue(da_filename);
VALUE tail_filename = rb_str_dup(filename_base);
rb_str_concat(tail_filename, rb_str_new2(".tail"));
StringValue(tail_filename);
Trie *trie = trie_new();
VALUE obj;
obj = Data_Wrap_Struct(self, 0, trie_free, trie);
DArray *old_da = trie->da;
Tail *old_tail = trie->tail;
FILE *da_file = fopen(RSTRING_PTR(da_filename), "r");
if (da_file == NULL)
raise_ioerror("Error reading .da file.");
trie->da = da_read(da_file);
fclose(da_file);
FILE *tail_file = fopen(RSTRING_PTR(tail_filename), "r");
if (tail_file == NULL)
raise_ioerror("Error reading .tail file.");
trie->tail = tail_read(tail_file);
fclose(tail_file);
da_free(old_da);
tail_free(old_tail);
return obj;
}
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Instance Method Details
#add(key) ⇒ Object #add(key, value) ⇒ Object
Add a key, or a key and value to the Trie. If you add a key without a value it assumes true for the value.
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# File 'ext/trie/trie.c', line 119
static VALUE rb_trie_add(VALUE self, VALUE args) {
Trie *trie;
Data_Get_Struct(self, Trie, trie);
int size = RARRAY_LEN(args);
if(size < 1 || size > 2)
return Qnil;
VALUE key;
key = RARRAY_PTR(args)[0];
StringValue(key);
TrieData value = size == 2 ? RARRAY_PTR(args)[1] : TRIE_DATA_ERROR;
if(trie_store(trie, (TrieChar*)RSTRING_PTR(key), value))
return Qtrue;
else
return Qnil;
}
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#children(prefix) ⇒ Array
Finds all keys in the Trie beginning with the given prefix.
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# File 'ext/trie/trie.c', line 189
static VALUE rb_trie_children(VALUE self, VALUE prefix) {
if(NIL_P(prefix))
return rb_ary_new();
StringValue(prefix);
Trie *trie;
Data_Get_Struct(self, Trie, trie);
int prefix_size = RSTRING_LEN(prefix);
TrieState *state = trie_root(trie);
VALUE children = rb_ary_new();
TrieChar *char_prefix = (TrieChar*)RSTRING_PTR(prefix);
const TrieChar *iterator = char_prefix;
while(*iterator != 0) {
if(!trie_state_is_walkable(state, *iterator))
return children;
trie_state_walk(state, *iterator);
iterator++;
}
if(trie_state_is_terminal(state))
rb_ary_push(children, prefix);
char prefix_buffer[1024];
memcpy(prefix_buffer, char_prefix, prefix_size);
prefix_buffer[prefix_size] = 0;
walk_all_paths(trie, children, state, prefix_buffer, prefix_size);
trie_state_free(state);
return children;
}
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#children_with_values(key) ⇒ Array
Finds all keys with their respective values in the Trie beginning with the given prefix.
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# File 'ext/trie/trie.c', line 267
static VALUE rb_trie_children_with_values(VALUE self, VALUE prefix) {
if(NIL_P(prefix))
return rb_ary_new();
StringValue(prefix);
Trie *trie;
Data_Get_Struct(self, Trie, trie);
int prefix_size = RSTRING_LEN(prefix);
TrieChar *char_prefix = (TrieChar*)RSTRING_PTR(prefix);
VALUE children = rb_ary_new();
TrieState *state = trie_root(trie);
const TrieChar *iterator = char_prefix;
while(*iterator != 0) {
if(!trie_state_is_walkable(state, *iterator))
return rb_ary_new();
trie_state_walk(state, *iterator);
iterator++;
}
if(trie_state_is_terminal(state)) {
TrieState *end_state = trie_state_clone(state);
trie_state_walk(end_state, '\0');
VALUE tuple = rb_ary_new();
rb_ary_push(tuple, prefix);
TrieData trie_data = trie_state_get_data(end_state);
rb_ary_push(tuple, (VALUE)trie_data);
rb_ary_push(children, tuple);
trie_state_free(end_state);
}
char prefix_buffer[1024];
memcpy(prefix_buffer, char_prefix, prefix_size);
prefix_buffer[prefix_size] = 0;
walk_all_paths_with_values(trie, children, state, prefix_buffer, prefix_size);
trie_state_free(state);
return children;
}
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#delete(key) ⇒ Object
Delete a key from the Trie. Returns true if it deleted a key, nil otherwise.
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# File 'ext/trie/trie.c', line 146
static VALUE rb_trie_delete(VALUE self, VALUE key) {
StringValue(key);
Trie *trie;
Data_Get_Struct(self, Trie, trie);
if(trie_delete(trie, (TrieChar*)RSTRING_PTR(key)))
return Qtrue;
else
return Qnil;
}
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#get(key) ⇒ Object
Retrieves the value for a particular key (or nil) from the Trie.
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# File 'ext/trie/trie.c', line 98
static VALUE rb_trie_get(VALUE self, VALUE key) {
StringValue(key);
Trie *trie;
Data_Get_Struct(self, Trie, trie);
TrieData data;
if(trie_retrieve(trie, (TrieChar*)RSTRING_PTR(key), &data))
return (VALUE)data;
else
return Qnil;
}
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#has_key?(key) ⇒ Boolean
Determines whether or not a key exists in the Trie. Use this if you don’t care about the value, as it is marginally faster than Trie#get.
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# File 'ext/trie/trie.c', line 78
static VALUE rb_trie_has_key(VALUE self, VALUE key) {
StringValue(key);
Trie *trie;
Data_Get_Struct(self, Trie, trie);
if(trie_has_key(trie, (TrieChar*)RSTRING_PTR(key)))
return Qtrue;
else
return Qnil;
}
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#root ⇒ TrieNode
Returns a TrieNode representing the root of the Trie.
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# File 'ext/trie/trie.c', line 323
static VALUE rb_trie_root(VALUE self) {
Trie *trie;
Data_Get_Struct(self, Trie, trie);
VALUE trie_node = rb_trie_node_alloc(cTrieNode);
TrieState *state = trie_root(trie);
RDATA(trie_node)->data = state;
rb_iv_set(trie_node, "@state", Qnil);
rb_iv_set(trie_node, "@full_state", rb_str_new2(""));
return trie_node;
}
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#save(filename_base) ⇒ true
Saves the trie data to two files, filename_base.da and filename_base.tail. Returns true if saving was successful.
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# File 'ext/trie/trie.c', line 504
static VALUE rb_trie_save(VALUE self, VALUE filename_base) {
VALUE da_filename = rb_str_dup(filename_base);
rb_str_concat(da_filename, rb_str_new2(".da"));
StringValue(da_filename);
VALUE tail_filename = rb_str_dup(filename_base);
rb_str_concat(tail_filename, rb_str_new2(".tail"));
StringValue(tail_filename);
Trie *trie;
Data_Get_Struct(self, Trie, trie);
FILE *da_file = fopen(RSTRING_PTR(da_filename), "w");
if (da_file == NULL)
raise_ioerror("Error opening .da file for writing.");
if (da_write(trie->da, da_file) != 0)
raise_ioerror("Error writing DArray data.");
fclose(da_file);
FILE *tail_file = fopen(RSTRING_PTR(tail_filename), "w");
if (tail_file == NULL)
raise_ioerror("Error opening .tail file for writing.");
if (tail_write(trie->tail, tail_file) != 0)
raise_ioerror("Error writing Tail data.");
fclose(tail_file);
return Qtrue;
}
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