485 lines
11 KiB
C++
485 lines
11 KiB
C++
#pragma once
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///@file
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#include <cassert>
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#include <climits>
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#include <span>
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#include "symbol-table.hh"
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#include "value/context.hh"
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#include "input-accessor.hh"
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#include "source-path.hh"
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#include "print-options.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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#include <nlohmann/json_fwd.hpp>
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namespace nix {
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class BindingsBuilder;
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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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tPrimOp,
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tPrimOpApp,
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tExternal,
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tFloat
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} InternalType;
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/**
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* This type abstracts over all actual value types in the language,
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* grouping together implementation details like tList*, different function
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* types, and types in non-normal form (so thunks and co.)
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*/
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typedef enum {
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nThunk,
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nInt,
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nFloat,
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nBool,
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nString,
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nPath,
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nNull,
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nAttrs,
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nList,
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nFunction,
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nExternal
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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 ExprBlackHole;
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struct PrimOp;
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class Symbol;
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class PosIdx;
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struct Pos;
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class StorePath;
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class EvalState;
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class XMLWriter;
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class Printer;
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typedef int64_t NixInt;
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typedef double NixFloat;
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/**
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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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friend class Printer;
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protected:
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/**
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* Print out the value
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*/
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virtual std::ostream & print(std::ostream & str) const = 0;
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public:
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/**
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* Return a simple string describing the type
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*/
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virtual std::string showType() const = 0;
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/**
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* Return a string to be used in builtins.typeOf
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*/
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virtual std::string typeOf() const = 0;
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/**
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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 std::string coerceToString(const Pos & pos, NixStringContext & context, bool copyMore, bool copyToStore) const;
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/**
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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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/**
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* Print the value as JSON. Defaults to unconvertable, i.e. throws an error
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*/
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virtual nlohmann::json printValueAsJSON(EvalState & state, bool strict,
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NixStringContext & context, bool copyToStore = true) const;
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/**
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* Print the value as XML. Defaults to unevaluated
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*/
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virtual void printValueAsXML(EvalState & state, bool strict, bool location,
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XMLWriter & doc, NixStringContext & context, PathSet & drvsSeen,
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const PosIdx pos) 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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private:
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InternalType internalType;
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friend std::string showType(const Value & v);
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public:
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void print(EvalState &state, std::ostream &str, PrintOptions options = PrintOptions {});
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// Functions needed to distinguish the type
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// These should be removed eventually, by putting the functionality that's
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// needed by callers into methods of this type
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// type() == nThunk
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inline bool isThunk() const { return internalType == tThunk; };
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inline bool isApp() const { return internalType == tApp; };
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inline bool isBlackhole() const;
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// type() == nFunction
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inline bool isLambda() const { return internalType == tLambda; };
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inline bool isPrimOp() const { return internalType == tPrimOp; };
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inline bool isPrimOpApp() const { return internalType == tPrimOpApp; };
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/**
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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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*
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* "--with-freetype2-library=" + freetype + "/lib"
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*
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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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*/
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struct StringWithContext {
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const char * c_str;
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const char * * context; // must be in sorted order
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};
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struct Path {
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InputAccessor * accessor;
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const char * path;
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};
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struct ClosureThunk {
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Env * env;
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Expr * expr;
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};
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struct FunctionApplicationThunk {
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Value * left, * right;
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};
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struct Lambda {
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Env * env;
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ExprLambda * fun;
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};
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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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StringWithContext string;
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Path _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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ClosureThunk thunk;
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FunctionApplicationThunk app;
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Lambda lambda;
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PrimOp * primOp;
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FunctionApplicationThunk primOpApp;
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ExternalValueBase * external;
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NixFloat fpoint;
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};
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/**
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* Returns the normal type of a Value. This only returns nThunk if
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* the Value hasn't been forceValue'd
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*
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* @param invalidIsThunk Instead of aborting an an invalid (probably
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* 0, so uninitialized) internal type, return `nThunk`.
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*/
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inline ValueType type(bool invalidIsThunk = false) const
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{
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switch (internalType) {
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case tInt: return nInt;
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case tBool: return nBool;
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case tString: return nString;
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case tPath: return nPath;
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case tNull: return nNull;
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case tAttrs: return nAttrs;
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case tList1: case tList2: case tListN: return nList;
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case tLambda: case tPrimOp: case tPrimOpApp: return nFunction;
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case tExternal: return nExternal;
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case tFloat: return nFloat;
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case tThunk: case tApp: return nThunk;
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}
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if (invalidIsThunk)
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return nThunk;
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else
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abort();
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}
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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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*/
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inline void clearValue()
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{
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app.left = app.right = 0;
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}
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inline void mkInt(NixInt n)
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{
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clearValue();
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internalType = tInt;
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integer = n;
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}
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inline void mkBool(bool b)
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{
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clearValue();
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internalType = tBool;
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boolean = b;
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}
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inline void mkString(const char * s, const char * * context = 0)
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{
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internalType = tString;
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string.c_str = s;
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string.context = context;
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}
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void mkString(std::string_view s);
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void mkString(std::string_view s, const NixStringContext & context);
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void mkStringMove(const char * s, const NixStringContext & context);
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inline void mkString(const Symbol & s)
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{
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mkString(((const std::string &) s).c_str());
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}
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void mkPath(const SourcePath & path);
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inline void mkPath(InputAccessor * accessor, const char * path)
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{
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clearValue();
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internalType = tPath;
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_path.accessor = accessor;
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_path.path = path;
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}
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inline void mkNull()
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{
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clearValue();
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internalType = tNull;
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}
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inline void mkAttrs(Bindings * a)
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{
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clearValue();
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internalType = tAttrs;
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attrs = a;
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}
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Value & mkAttrs(BindingsBuilder & bindings);
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inline void mkList(size_t size)
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{
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clearValue();
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if (size == 1)
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internalType = tList1;
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else if (size == 2)
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internalType = tList2;
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else {
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internalType = tListN;
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bigList.size = size;
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}
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}
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inline void mkThunk(Env * e, Expr * ex)
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{
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internalType = tThunk;
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thunk.env = e;
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thunk.expr = ex;
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}
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inline void mkApp(Value * l, Value * r)
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{
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internalType = tApp;
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app.left = l;
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app.right = r;
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}
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inline void mkLambda(Env * e, ExprLambda * f)
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{
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internalType = tLambda;
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lambda.env = e;
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lambda.fun = f;
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}
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inline void mkBlackhole();
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void mkPrimOp(PrimOp * p);
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inline void mkPrimOpApp(Value * l, Value * r)
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{
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internalType = tPrimOpApp;
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primOpApp.left = l;
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primOpApp.right = r;
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}
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/**
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* For a `tPrimOpApp` value, get the original `PrimOp` value.
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*/
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PrimOp * primOpAppPrimOp() const;
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inline void mkExternal(ExternalValueBase * e)
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{
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clearValue();
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internalType = tExternal;
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external = e;
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}
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inline void mkFloat(NixFloat n)
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{
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clearValue();
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internalType = tFloat;
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fpoint = n;
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}
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bool isList() const
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{
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return internalType == tList1 || internalType == tList2 || internalType == tListN;
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}
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Value * * listElems()
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{
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return internalType == tList1 || internalType == tList2 ? smallList : bigList.elems;
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}
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std::span<Value * const> listItems() const
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{
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assert(isList());
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return std::span<Value * const>(listElems(), listSize());
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}
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Value * const * listElems() const
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{
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return internalType == tList1 || internalType == 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 internalType == tList1 ? 1 : internalType == tList2 ? 2 : bigList.size;
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}
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PosIdx determinePos(const PosIdx pos) const;
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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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*/
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bool isTrivial() const;
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SourcePath path() const
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{
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assert(internalType == tPath);
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return SourcePath(
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ref(_path.accessor->shared_from_this()),
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CanonPath(CanonPath::unchecked_t(), _path.path));
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}
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std::string_view string_view() const
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{
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assert(internalType == tString);
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return std::string_view(string.c_str);
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}
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const char * const c_str() const
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{
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assert(internalType == tString);
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return string.c_str;
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}
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const char * * context() const
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{
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return string.context;
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}
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};
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extern ExprBlackHole eBlackHole;
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bool Value::isBlackhole() const
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{
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return internalType == tThunk && thunk.expr == (Expr*) &eBlackHole;
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}
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void Value::mkBlackhole()
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{
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internalType = tThunk;
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thunk.expr = (Expr*) &eBlackHole;
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}
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#if HAVE_BOEHMGC
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typedef std::vector<Value *, traceable_allocator<Value *>> ValueVector;
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typedef std::map<Symbol, Value *, std::less<Symbol>, traceable_allocator<std::pair<const Symbol, Value *>>> ValueMap;
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typedef std::map<Symbol, ValueVector, std::less<Symbol>, traceable_allocator<std::pair<const Symbol, ValueVector>>> ValueVectorMap;
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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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typedef std::map<Symbol, ValueVector> ValueVectorMap;
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#endif
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/**
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* A value allocated in traceable memory.
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*/
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typedef std::shared_ptr<Value *> RootValue;
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RootValue allocRootValue(Value * v);
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}
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