forked from lix-project/lix
280 lines
6.4 KiB
C++
280 lines
6.4 KiB
C++
#pragma once
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#include "symbol-table.hh"
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#if HAVE_BOEHMGC
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#include <gc/gc_allocator.h>
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#endif
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namespace nix {
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typedef enum {
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tInt = 1,
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tBool,
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tString,
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tPath,
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tNull,
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tAttrs,
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tList1,
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tList2,
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tListN,
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tThunk,
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tApp,
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tLambda,
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tBlackhole,
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tPrimOp,
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tPrimOpApp,
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tExternal,
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tFloat
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} ValueType;
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class Bindings;
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struct Env;
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struct Expr;
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struct ExprLambda;
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struct PrimOp;
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struct PrimOp;
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class Symbol;
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struct Pos;
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class EvalState;
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class XMLWriter;
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class JSONPlaceholder;
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typedef int64_t NixInt;
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typedef double NixFloat;
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/* External values must descend from ExternalValueBase, so that
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* type-agnostic nix functions (e.g. showType) can be implemented
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*/
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class ExternalValueBase
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{
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friend std::ostream & operator << (std::ostream & str, const ExternalValueBase & v);
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protected:
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/* Print out the value */
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virtual std::ostream & print(std::ostream & str) const = 0;
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public:
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/* Return a simple string describing the type */
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virtual string showType() const = 0;
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/* Return a string to be used in builtins.typeOf */
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virtual string typeOf() const = 0;
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/* How much space does this value take up */
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virtual size_t valueSize(std::set<const void *> & seen) const = 0;
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/* Coerce the value to a string. Defaults to uncoercable, i.e. throws an
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* error
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*/
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virtual string coerceToString(const Pos & pos, PathSet & context, bool copyMore, bool copyToStore) const;
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/* Compare to another value of the same type. Defaults to uncomparable,
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* i.e. always false.
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*/
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virtual bool operator==(const ExternalValueBase & b) const;
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/* Print the value as JSON. Defaults to unconvertable, i.e. throws an error */
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virtual void printValueAsJSON(EvalState & state, bool strict,
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JSONPlaceholder & out, PathSet & context) const;
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/* Print the value as XML. Defaults to unevaluated */
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virtual void printValueAsXML(EvalState & state, bool strict, bool location,
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XMLWriter & doc, PathSet & context, PathSet & drvsSeen) const;
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virtual ~ExternalValueBase()
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{
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};
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};
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std::ostream & operator << (std::ostream & str, const ExternalValueBase & v);
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struct Value
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{
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ValueType type;
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union
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{
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NixInt integer;
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bool boolean;
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/* Strings in the evaluator carry a so-called `context' which
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is a list of strings representing store paths. This is to
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allow users to write things like
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"--with-freetype2-library=" + freetype + "/lib"
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where `freetype' is a derivation (or a source to be copied
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to the store). If we just concatenated the strings without
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keeping track of the referenced store paths, then if the
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string is used as a derivation attribute, the derivation
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will not have the correct dependencies in its inputDrvs and
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inputSrcs.
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The semantics of the context is as follows: when a string
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with context C is used as a derivation attribute, then the
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derivations in C will be added to the inputDrvs of the
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derivation, and the other store paths in C will be added to
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the inputSrcs of the derivations.
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For canonicity, the store paths should be in sorted order. */
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struct {
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const char * s;
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const char * * context; // must be in sorted order
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} string;
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const char * path;
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Bindings * attrs;
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struct {
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size_t size;
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Value * * elems;
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} bigList;
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Value * smallList[2];
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struct {
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Env * env;
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Expr * expr;
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} thunk;
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struct {
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Value * left, * right;
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} app;
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struct {
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Env * env;
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ExprLambda * fun;
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} lambda;
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PrimOp * primOp;
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struct {
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Value * left, * right;
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} primOpApp;
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ExternalValueBase * external;
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NixFloat fpoint;
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};
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bool isList() const
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{
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return type == tList1 || type == tList2 || type == tListN;
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}
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Value * * listElems()
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{
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return type == tList1 || type == tList2 ? smallList : bigList.elems;
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}
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const Value * const * listElems() const
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{
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return type == tList1 || type == tList2 ? smallList : bigList.elems;
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}
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size_t listSize() const
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{
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return type == tList1 ? 1 : type == tList2 ? 2 : bigList.size;
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}
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/* Check whether forcing this value requires a trivial amount of
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computation. In particular, function applications are
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non-trivial. */
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bool isTrivial() const;
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};
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/* After overwriting an app node, be sure to clear pointers in the
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Value to ensure that the target isn't kept alive unnecessarily. */
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static inline void clearValue(Value & v)
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{
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v.app.left = v.app.right = 0;
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}
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static inline void mkInt(Value & v, NixInt n)
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{
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clearValue(v);
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v.type = tInt;
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v.integer = n;
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}
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static inline void mkFloat(Value & v, NixFloat n)
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{
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clearValue(v);
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v.type = tFloat;
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v.fpoint = n;
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}
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static inline void mkBool(Value & v, bool b)
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{
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clearValue(v);
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v.type = tBool;
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v.boolean = b;
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}
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static inline void mkNull(Value & v)
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{
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clearValue(v);
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v.type = tNull;
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}
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static inline void mkApp(Value & v, Value & left, Value & right)
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{
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v.type = tApp;
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v.app.left = &left;
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v.app.right = &right;
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}
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static inline void mkPrimOpApp(Value & v, Value & left, Value & right)
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{
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v.type = tPrimOpApp;
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v.app.left = &left;
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v.app.right = &right;
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}
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static inline void mkStringNoCopy(Value & v, const char * s)
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{
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v.type = tString;
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v.string.s = s;
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v.string.context = 0;
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}
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static inline void mkString(Value & v, const Symbol & s)
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{
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mkStringNoCopy(v, ((const string &) s).c_str());
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}
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void mkString(Value & v, const char * s);
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static inline void mkPathNoCopy(Value & v, const char * s)
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{
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clearValue(v);
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v.type = tPath;
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v.path = s;
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}
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void mkPath(Value & v, const char * s);
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/* Compute the size in bytes of the given value, including all values
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and environments reachable from it. Static expressions (Exprs) are
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not included. */
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size_t valueSize(Value & v);
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#if HAVE_BOEHMGC
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typedef std::vector<Value *, gc_allocator<Value *> > ValueVector;
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typedef std::map<Symbol, Value *, std::less<Symbol>, gc_allocator<std::pair<const Symbol, Value *> > > ValueMap;
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#else
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typedef std::vector<Value *> ValueVector;
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typedef std::map<Symbol, Value *> ValueMap;
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#endif
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}
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