1#pragma once
2
3#include "llama.h"
4
5#include "common.h"
6
7#include <string>
8#include <vector>
9
10// common_sampler extends llama_sampler with additional functionality:
11//
12// - grammar support
13// - custom sampler logic based on the parameters
14// - history of the last accepted tokens
15// - performance metrics
16//
17// This goal is to have a common implementation of the sampling logic shared across the examples.
18// For example, depending on the temperature, the sampling chain can be very simple (greedy) or more
19// complex (top-k, top-p, etc).
20//
21// Another example is related to the grammar. In general, the grammar constraints applied on the full
22// vocabulary can be very taxing. To improve performance, the grammar can be applied only to the sampled
23// token in order to verify if it fits the grammar. And only if the token doesn't fit the grammar, the
24// grammar constraints are applied to the full vocabulary and the token is resampled.
25//
26// The common_sampler also maintains a container with the last accepted tokens. In the future, this can
27// be moved into the core llama library.
28//
29// For convenience, the common_sampler also maintains a container with the current candidate tokens.
30// This can be used to access the probabilities of the rest of the non-sampled tokens.
31//
32// TODO: measure grammar performance
33//
34
35struct common_sampler;
36
37// llama_sampler API overloads
38
39struct common_sampler * common_sampler_init(const struct llama_model * model, const struct common_params_sampling & params);
40
41void common_sampler_free(struct common_sampler * gsmpl);
42
43// if accept_grammar is true, the token is accepted both by the sampling chain and the grammar
44void common_sampler_accept(struct common_sampler * gsmpl, llama_token token, bool accept_grammar);
45void common_sampler_reset (struct common_sampler * gsmpl);
46struct common_sampler * common_sampler_clone (struct common_sampler * gsmpl);
47
48// arguments can be nullptr to skip printing
49void common_perf_print(const struct llama_context * ctx, const struct common_sampler * gsmpl);
50
51// extended sampling implementation:
52//
53// - set logits
54// - apply the configured sampler chain
55// - check if the token fits the grammar (if any)
56// - if not: resample by first applying the grammar constraints and then sampling again (slower path)
57//
58// if grammar_first is true, the grammar is applied before the samplers (slower)
59// useful in cases where all the resulting candidates (not just the sampled one) must fit the grammar
60//
61llama_token common_sampler_sample(struct common_sampler * gsmpl, struct llama_context * ctx, int idx, bool grammar_first = false);
62
63// generalized version of common_sampler_sample
64//
65// will cross-reference the sampled tokens with a batch of draft tokens and accept those that match
66// if the sampler disagrees at some point, we stop and return the accepted tokens up to now
67//
68// common_sampler_sample_n(gsmpl, ctx, { idx }, {});
69//
70// is equivalent to
71//
72// common_sampler_sample(gsmpl, ctx, idx);
73// common_sampler_accept(gsmpl, token, true);
74//
75// requires: idxs.size() == draft.size() + 1
76//
77// returns at least 1 token, up to idxs.size()
78//
79std::vector<llama_token> common_sampler_sample_and_accept_n(struct common_sampler * gsmpl, struct llama_context * ctx, const std::vector<int> & idxs, const llama_tokens & draft, bool grammar_first = false);
80
81// assume idxs == [ 0, 1, 2, ..., draft.size() ]
82std::vector<llama_token> common_sampler_sample_and_accept_n(struct common_sampler * gsmpl, struct llama_context * ctx, const llama_tokens & draft, bool grammar_first = false);
83
84uint32_t common_sampler_get_seed(const struct common_sampler * gsmpl);
85
86// helpers
87
88// access the internal list of current candidate tokens
89// if do_sort == true, the candidates are guaranteed to be sorted afterwards (in descending order of probability)
90// the .sorted flag of the result indicates whether the returned candidates are sorted
91llama_token_data_array * common_sampler_get_candidates(struct common_sampler * gsmpl, bool do_sort);
92
93// get the last accepted token
94llama_token common_sampler_last(const struct common_sampler * gsmpl);
95
96// print the sampler chain into a string
97std::string common_sampler_print(const struct common_sampler * gsmpl);
98
99// get a string representation of the last accepted tokens
100std::string common_sampler_prev_str(common_sampler * gsmpl, llama_context * ctx, int n);
101
102char common_sampler_type_to_chr(enum common_sampler_type cnstr);
103std::string common_sampler_type_to_str(enum common_sampler_type cnstr);
104
105std::vector<enum common_sampler_type> common_sampler_types_from_names(const std::vector<std::string> & names, bool allow_alt_names);
106std::vector<enum common_sampler_type> common_sampler_types_from_chars(const std::string & chars);
107
108llama_sampler * llama_sampler_init_llg(const llama_vocab * vocab,
109 const char * grammar_kind, const char * grammar_data);
110