separate header/impl for strman
parent
4588ae2373
commit
6821260c37
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@ -298,10 +298,10 @@ LIBCUBESCRIPT_EXPORT bool cs_code_is_empty(cs_bcode *code);
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struct LIBCUBESCRIPT_EXPORT cs_strref {
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friend struct cs_value;
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/* FIXME: eliminate this */
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friend inline cs_strref cs_make_strref(char const *p, cs_shared_state &cs);
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friend inline cs_strref cs_make_strref(char const *p, cs_shared_state *cs);
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cs_strref() = delete;
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cs_strref(cs_shared_state &cs, std::string_view str);
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cs_strref(cs_shared_state *cs, std::string_view str);
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cs_strref(cs_state &cs, std::string_view str);
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cs_strref(cs_strref const &ref);
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@ -327,7 +327,7 @@ struct LIBCUBESCRIPT_EXPORT cs_strref {
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private:
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/* for internal use only */
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cs_strref(char const *p, cs_shared_state &cs);
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cs_strref(char const *p, cs_shared_state *cs);
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cs_shared_state *p_state;
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char const *p_str;
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@ -3,6 +3,7 @@
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#include "cs_util.hh"
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#include "cs_bcode.hh"
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#include "cs_state.hh"
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#include "cs_strman.hh"
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namespace cscript {
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@ -0,0 +1,112 @@
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#include <cubescript/cubescript.hh>
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#include "cs_strman.hh"
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namespace cscript {
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struct cs_strref_state {
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std::size_t length;
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std::size_t refcount;
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};
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inline cs_strref_state *get_ref_state(char const *ptr) {
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return const_cast<cs_strref_state *>(
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reinterpret_cast<cs_strref_state const *>(ptr)
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) - 1;
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}
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char const *cs_strman::add(std::string_view str) {
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auto it = counts.find(str);
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/* already present: just increment ref */
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if (it != counts.end()) {
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auto *st = it->second;
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/* having a null pointer is the same as non-existence */
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if (st) {
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++st->refcount;
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return reinterpret_cast<char const *>(st + 1);
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}
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}
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/* not present: allocate brand new data */
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auto ss = str.size();
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auto strp = alloc_buf(ss);
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/* write string data, it's already pre-terminated */
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memcpy(strp, str.data(), ss);
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/* store it */
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counts.emplace(std::string_view{strp, ss}, get_ref_state(strp));
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return strp;
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}
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char const *cs_strman::ref(char const *ptr) {
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auto *ss = get_ref_state(ptr);
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++ss->refcount;
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return ptr;
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}
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char const *cs_strman::steal(char *ptr) {
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auto *ss = get_ref_state(ptr);
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auto sr = std::string_view{ptr, ss->length};
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/* much like add(), but we already have memory */
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auto it = counts.find(sr);
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if (it != counts.end()) {
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auto *st = it->second;
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if (st) {
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++st->refcount;
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/* the buffer is superfluous now */
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cstate->alloc(ss, ss->length + sizeof(cs_strref_state) + 1, 0);
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return reinterpret_cast<char const *>(st + 1);
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}
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}
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ss->refcount = 1;
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counts.emplace(sr, ss);
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return ptr;
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}
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void cs_strman::unref(char const *ptr) {
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auto *ss = get_ref_state(ptr);
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if (!--ss->refcount) {
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/* refcount zero, so ditch it
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* this path is a little slow...
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*/
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auto sr = std::string_view{ptr, ss->length};
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auto it = counts.find(sr);
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if (it == counts.end()) {
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/* internal error: this should *never* happen */
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throw cs_internal_error{"no refcount"};
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}
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/* we're freeing the key */
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counts.erase(it);
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/* dealloc */
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cstate->alloc(ss, ss->length + sizeof(cs_strref_state) + 1, 0);
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}
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}
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char const *cs_strman::find(std::string_view str) const {
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auto it = counts.find(str);
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if (it == counts.end()) {
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return nullptr;
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}
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return reinterpret_cast<char const *>(it->second + 1);
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}
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std::string_view cs_strman::get(char const *ptr) const {
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auto *ss = get_ref_state(ptr);
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return std::string_view{ptr, ss->length};
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}
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char *cs_strman::alloc_buf(std::size_t len) const {
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auto mem = cstate->alloc(nullptr, 0, len + sizeof(cs_strref_state) + 1);
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if (!mem) {
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throw cs_internal_error{"allocation failed"};
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}
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/* write length and initial refcount */
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auto *sst = static_cast<cs_strref_state *>(mem);
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sst->length = len;
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sst->refcount = 1;
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/* pre-terminate */
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auto *strp = reinterpret_cast<char *>(sst + 1);
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strp[len] = '\0';
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/* now the user can fill it */
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return strp;
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};
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} /* namespace cscript */
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@ -0,0 +1,92 @@
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#ifndef LIBCUBESCRIPT_STRMAN_HH
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#define LIBCUBESCRIPT_STRMAN_HH
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#include <cubescript/cubescript.hh>
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#include <unordered_map>
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#include <string_view>
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#include "cs_std.hh"
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#include "cs_state.hh"
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namespace cscript {
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struct cs_strref_state;
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/* string manager
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*
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* the purpose of this is to handle interning of strings; each string within
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* a libcs state is represented (and allocated) exactly once, and reference
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* counted; that both helps save resources, and potentially provide a means
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* to reliably represent returned strings in places that is compatible with
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* multiple threads and eliminate the chance of dangling pointers
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*
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* strings are allocated in a manner where the refcount and length are stored
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* as a part of the string's memory, so it can be easily accessed using just
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* the pointer to the string, but also this is transparent for usage
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*
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* this is not thread-safe yet, and later on it should be made that,
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* for now we don't bother...
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*/
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struct cs_strman {
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using allocator_type = cs_allocator<
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std::pair<std::string_view const, cs_strref_state *>
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>;
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cs_strman() = delete;
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cs_strman(cs_shared_state *cs): cstate{cs}, counts{allocator_type{cs}} {}
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~cs_strman() {}
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cs_strman(cs_strman const &) = delete;
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cs_strman(cs_strman &&) = delete;
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cs_strman &operator=(cs_strman const &) = delete;
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cs_strman &operator=(cs_strman &&) = delete;
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/* adds a string into the manager using any source, and returns a managed
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* version; this is "slow" as it has to hash the string and potentially
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* allocate fresh memory for it, but is perfectly safe at any time
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*/
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char const *add(std::string_view str);
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/* this simply increments the reference count of an existing managed
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* string, this is only safe when you know the pointer you are passing
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* is already managed the system
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*/
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char const *ref(char const *ptr);
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/* this will use the provided memory, assuming it is a fresh string that
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* is yet to be added; the memory must be allocated with alloc_buf()
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*/
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char const *steal(char *ptr);
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/* decrements the reference count and removes it from the system if
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* that reaches zero; likewise, only safe with pointers that are managed
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*/
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void unref(char const *ptr);
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/* just finds a managed pointer with the same contents
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* as the input, if not found then a null pointer is returned
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*/
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char const *find(std::string_view str) const;
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/* a quick helper to make a proper string view out of a ptr */
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std::string_view get(char const *ptr) const;
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/* this will allocate a buffer of the given length (plus one for
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* terminating zero) so you can fill it; use steal() to write it
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*/
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char *alloc_buf(std::size_t len) const;
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cs_shared_state *cstate;
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std::unordered_map<
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std::string_view, cs_strref_state *,
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std::hash<std::string_view>,
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std::equal_to<std::string_view>,
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allocator_type
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> counts;
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};
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} /* namespace cscript */
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#endif
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103
src/cs_util.cc
103
src/cs_util.cc
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@ -1,6 +1,7 @@
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#include <cubescript/cubescript.hh>
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#include "cs_util.hh"
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#include "cs_vm.hh"
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#include "cs_strman.hh"
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#include <cctype>
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#include <cmath>
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@ -182,108 +183,6 @@ done:
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return ret;
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}
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/* string manager */
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inline cs_strref_state *get_ref_state(char const *ptr) {
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return const_cast<cs_strref_state *>(
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reinterpret_cast<cs_strref_state const *>(ptr)
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) - 1;
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}
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char const *cs_strman::add(std::string_view str) {
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auto it = counts.find(str);
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/* already present: just increment ref */
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if (it != counts.end()) {
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auto *st = it->second;
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/* having a null pointer is the same as non-existence */
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if (st) {
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++st->refcount;
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return reinterpret_cast<char const *>(st + 1);
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}
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}
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/* not present: allocate brand new data */
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auto ss = str.size();
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auto strp = alloc_buf(ss);
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/* write string data, it's already pre-terminated */
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memcpy(strp, str.data(), ss);
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/* store it */
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counts.emplace(std::string_view{strp, ss}, get_ref_state(strp));
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return strp;
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}
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char const *cs_strman::ref(char const *ptr) {
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auto *ss = get_ref_state(ptr);
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++ss->refcount;
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return ptr;
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}
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char const *cs_strman::steal(char *ptr) {
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auto *ss = get_ref_state(ptr);
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auto sr = std::string_view{ptr, ss->length};
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/* much like add(), but we already have memory */
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auto it = counts.find(sr);
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if (it != counts.end()) {
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auto *st = it->second;
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if (st) {
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++st->refcount;
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/* the buffer is superfluous now */
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cstate->alloc(ss, ss->length + sizeof(cs_strref_state) + 1, 0);
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return reinterpret_cast<char const *>(st + 1);
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}
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}
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ss->refcount = 1;
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counts.emplace(sr, ss);
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return ptr;
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}
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void cs_strman::unref(char const *ptr) {
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auto *ss = get_ref_state(ptr);
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if (!--ss->refcount) {
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/* refcount zero, so ditch it
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* this path is a little slow...
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*/
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auto sr = std::string_view{ptr, ss->length};
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auto it = counts.find(sr);
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if (it == counts.end()) {
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/* internal error: this should *never* happen */
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throw cs_internal_error{"no refcount"};
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}
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/* we're freeing the key */
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counts.erase(it);
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/* dealloc */
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cstate->alloc(ss, ss->length + sizeof(cs_strref_state) + 1, 0);
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}
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}
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char const *cs_strman::find(std::string_view str) const {
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auto it = counts.find(str);
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if (it == counts.end()) {
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return nullptr;
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}
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return reinterpret_cast<char const *>(it->second + 1);
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}
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std::string_view cs_strman::get(char const *ptr) const {
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auto *ss = get_ref_state(ptr);
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return std::string_view{ptr, ss->length};
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}
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char *cs_strman::alloc_buf(std::size_t len) const {
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auto mem = cstate->alloc(nullptr, 0, len + sizeof(cs_strref_state) + 1);
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if (!mem) {
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throw cs_internal_error{"allocation failed"};
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}
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/* write length and initial refcount */
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auto *sst = static_cast<cs_strref_state *>(mem);
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sst->length = len;
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sst->refcount = 1;
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/* pre-terminate */
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auto *strp = reinterpret_cast<char *>(sst + 1);
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strp[len] = '\0';
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/* now the user can fill it */
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return strp;
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};
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/* strref */
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cs_strref::cs_strref(cs_shared_state *cs, std::string_view str):
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@ -25,85 +25,6 @@ inline cs_strref cs_make_strref(char const *p, cs_shared_state *cs) {
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return cs_strref{p, cs};
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}
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/* string manager
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*
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* the purpose of this is to handle interning of strings; each string within
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* a libcs state is represented (and allocated) exactly once, and reference
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* counted; that both helps save resources, and potentially provide a means
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* to reliably represent returned strings in places that is compatible with
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* multiple threads and eliminate the chance of dangling pointers
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*
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* strings are allocated in a manner where the refcount and length are stored
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* as a part of the string's memory, so it can be easily accessed using just
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* the pointer to the string, but also this is transparent for usage
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*
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* this is not thread-safe yet, and later on it should be made that,
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* for now we don't bother...
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*/
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struct cs_strref_state {
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size_t length;
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size_t refcount;
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};
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struct cs_strman {
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using allocator_type = cs_allocator<
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std::pair<std::string_view const, cs_strref_state *>
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>;
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cs_strman() = delete;
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cs_strman(cs_shared_state *cs): cstate{cs}, counts{allocator_type{cs}} {}
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~cs_strman() {}
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cs_strman(cs_strman const &) = delete;
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cs_strman(cs_strman &&) = delete;
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cs_strman &operator=(cs_strman const &) = delete;
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cs_strman &operator=(cs_strman &&) = delete;
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/* adds a string into the manager using any source, and returns a managed
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* version; this is "slow" as it has to hash the string and potentially
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* allocate fresh memory for it, but is perfectly safe at any time
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*/
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char const *add(std::string_view str);
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|
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/* this simply increments the reference count of an existing managed
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* string, this is only safe when you know the pointer you are passing
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* is already managed the system
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*/
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char const *ref(char const *ptr);
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/* this will use the provided memory, assuming it is a fresh string that
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* is yet to be added; the memory must be allocated with alloc_buf()
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*/
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char const *steal(char *ptr);
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/* decrements the reference count and removes it from the system if
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* that reaches zero; likewise, only safe with pointers that are managed
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*/
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void unref(char const *ptr);
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/* just finds a managed pointer with the same contents
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* as the input, if not found then a null pointer is returned
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*/
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char const *find(std::string_view str) const;
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/* a quick helper to make a proper string view out of a ptr */
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std::string_view get(char const *ptr) const;
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/* this will allocate a buffer of the given length (plus one for
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* terminating zero) so you can fill it; use steal() to write it
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*/
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char *alloc_buf(std::size_t len) const;
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cs_shared_state *cstate;
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std::unordered_map<
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std::string_view, cs_strref_state *,
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std::hash<std::string_view>,
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std::equal_to<std::string_view>,
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allocator_type
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> counts;
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};
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} /* namespace cscript */
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#endif /* LIBCUBESCRIPT_CS_UTIL_HH */
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@ -5,6 +5,7 @@
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#include "cs_util.hh"
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#include "cs_std.hh"
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#include "cs_strman.hh"
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namespace cscript {
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@ -9,6 +9,7 @@ libcubescript_src = [
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'cs_gen.cc',
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'cs_ident.cc',
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'cs_state.cc',
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'cs_strman.cc',
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'cs_util.cc',
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'cs_val.cc',
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'cs_vm.cc',
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