mirror of
https://github.com/privatevoid-net/nix-super.git
synced 2024-11-24 06:56:14 +02:00
511 lines
13 KiB
C++
511 lines
13 KiB
C++
#pragma once
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///@file
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#include <cassert>
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#include <span>
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#include "eval-gc.hh"
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#include "symbol-table.hh"
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#include "value/context.hh"
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#include "source-path.hh"
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#include "print-options.hh"
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#include "checked-arithmetic.hh"
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#include <nlohmann/json_fwd.hpp>
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namespace nix {
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struct Value;
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class BindingsBuilder;
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typedef enum {
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tUninitialized = 0,
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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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using NixInt = checked::Checked<int64_t>;
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using NixFloat = double;
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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(EvalState & state, const PosIdx & 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 noexcept;
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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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class ListBuilder
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{
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const size_t size;
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Value * inlineElems[2] = {nullptr, nullptr};
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public:
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Value * * elems;
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ListBuilder(EvalState & state, size_t size);
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ListBuilder(ListBuilder && x)
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: size(x.size)
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, inlineElems{x.inlineElems[0], x.inlineElems[1]}
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, elems(size <= 2 ? inlineElems : x.elems)
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{ }
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Value * & operator [](size_t n)
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{
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return elems[n];
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}
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typedef Value * * iterator;
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iterator begin() { return &elems[0]; }
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iterator end() { return &elems[size]; }
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friend struct Value;
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};
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struct Value
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{
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private:
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InternalType internalType = tUninitialized;
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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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SourceAccessor * 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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using Payload = 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 * const * 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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Payload payload;
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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 tUninitialized: break;
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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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unreachable();
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}
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inline void finishValue(InternalType newType, Payload newPayload)
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{
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payload = newPayload;
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internalType = newType;
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}
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/**
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* A value becomes valid when it is initialized. We don't use this
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* in the evaluator; only in the bindings, where the slight extra
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* cost is warranted because of inexperienced callers.
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*/
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inline bool isValid() const
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{
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return internalType != tUninitialized;
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}
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inline void mkInt(NixInt::Inner n)
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{
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mkInt(NixInt{n});
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}
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inline void mkInt(NixInt n)
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{
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finishValue(tInt, { .integer = n });
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}
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inline void mkBool(bool b)
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{
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finishValue(tBool, { .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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finishValue(tString, { .string = { .c_str = s, .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 SymbolStr & s)
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{
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mkString(s.c_str());
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}
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void mkPath(const SourcePath & path);
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void mkPath(std::string_view path);
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inline void mkPath(SourceAccessor * accessor, const char * path)
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{
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finishValue(tPath, { .path = { .accessor = accessor, .path = path } });
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}
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inline void mkNull()
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{
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finishValue(tNull, {});
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}
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inline void mkAttrs(Bindings * a)
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{
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finishValue(tAttrs, { .attrs = a });
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}
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Value & mkAttrs(BindingsBuilder & bindings);
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void mkList(const ListBuilder & builder)
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{
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if (builder.size == 1)
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finishValue(tList1, { .smallList = { builder.inlineElems[0] } });
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else if (builder.size == 2)
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finishValue(tList2, { .smallList = { builder.inlineElems[0], builder.inlineElems[1] } });
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else
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finishValue(tListN, { .bigList = { .size = builder.size, .elems = builder.elems } });
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}
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inline void mkThunk(Env * e, Expr * ex)
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{
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finishValue(tThunk, { .thunk = { .env = e, .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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finishValue(tApp, { .app = { .left = l, .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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finishValue(tLambda, { .lambda = { .env = e, .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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finishValue(tPrimOpApp, { .primOpApp = { .left = l, .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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const PrimOp * primOpAppPrimOp() const;
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inline void mkExternal(ExternalValueBase * e)
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{
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finishValue(tExternal, { .external = e });
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}
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inline void mkFloat(NixFloat n)
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{
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finishValue(tFloat, { .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 * const * listElems()
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{
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return internalType == tList1 || internalType == tList2 ? payload.smallList : payload.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 ? payload.smallList : payload.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 : payload.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(payload.path.accessor->shared_from_this()),
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CanonPath(CanonPath::unchecked_t(), payload.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(payload.string.c_str);
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}
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const char * c_str() const
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{
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assert(internalType == tString);
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return payload.string.c_str;
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}
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const char * * context() const
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{
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return payload.string.context;
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}
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ExternalValueBase * external() const
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{ return payload.external; }
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const Bindings * attrs() const
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{ return payload.attrs; }
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const PrimOp * primOp() const
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{ return payload.primOp; }
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bool boolean() const
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{ return payload.boolean; }
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NixInt integer() const
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{ return payload.integer; }
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NixFloat fpoint() const
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{ return payload.fpoint; }
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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 && payload.thunk.expr == (Expr*) &eBlackHole;
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}
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void Value::mkBlackhole()
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{
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mkThunk(nullptr, (Expr *) &eBlackHole);
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}
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typedef std::vector<Value *, traceable_allocator<Value *>> ValueVector;
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typedef std::unordered_map<Symbol, Value *, std::hash<Symbol>, std::equal_to<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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/**
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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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