lix/src/libexpr/nixexpr.hh
Andreas Rammhold cae41eebff libexpr: remove matchAttrs boolean from ExprLambda
The boolean is only used to determine if the formals are set to a
non-null pointer in all our cases. We can get rid of that allocation and
instead just compare the pointer value with NULL. Saving up to
sizeof(bool) + platform specific alignment per ExprLambda instace.
Probably not a lot of memory but perhaps a few kilobyte with nixpkgs?

This also gets rid of a potential issue with dereferencing formals based on
the value of the boolean that didn't have to be aligned with the formals
pointer but was in all our cases.
2021-10-06 17:24:06 +02:00

351 lines
8.6 KiB
C++

#pragma once
#include "value.hh"
#include "symbol-table.hh"
#include "error.hh"
#include <map>
namespace nix {
MakeError(EvalError, Error);
MakeError(ParseError, Error);
MakeError(AssertionError, EvalError);
MakeError(ThrownError, AssertionError);
MakeError(Abort, EvalError);
MakeError(TypeError, EvalError);
MakeError(UndefinedVarError, Error);
MakeError(MissingArgumentError, EvalError);
MakeError(RestrictedPathError, Error);
/* Position objects. */
struct Pos
{
FileOrigin origin;
Symbol file;
unsigned int line, column;
Pos() : origin(foString), line(0), column(0) { };
Pos(FileOrigin origin, const Symbol & file, unsigned int line, unsigned int column)
: origin(origin), file(file), line(line), column(column) { };
operator bool() const
{
return line != 0;
}
bool operator < (const Pos & p2) const
{
if (!line) return p2.line;
if (!p2.line) return false;
int d = ((string) file).compare((string) p2.file);
if (d < 0) return true;
if (d > 0) return false;
if (line < p2.line) return true;
if (line > p2.line) return false;
return column < p2.column;
}
};
extern Pos noPos;
std::ostream & operator << (std::ostream & str, const Pos & pos);
struct Env;
struct Value;
class EvalState;
struct StaticEnv;
/* An attribute path is a sequence of attribute names. */
struct AttrName
{
Symbol symbol;
Expr * expr;
AttrName(const Symbol & s) : symbol(s) {};
AttrName(Expr * e) : expr(e) {};
};
typedef std::vector<AttrName> AttrPath;
string showAttrPath(const AttrPath & attrPath);
/* Abstract syntax of Nix expressions. */
struct Expr
{
virtual ~Expr() { };
virtual void show(std::ostream & str) const;
virtual void bindVars(const StaticEnv & env);
virtual void eval(EvalState & state, Env & env, Value & v);
virtual Value * maybeThunk(EvalState & state, Env & env);
virtual void setName(Symbol & name);
};
std::ostream & operator << (std::ostream & str, const Expr & e);
#define COMMON_METHODS \
void show(std::ostream & str) const; \
void eval(EvalState & state, Env & env, Value & v); \
void bindVars(const StaticEnv & env);
struct ExprInt : Expr
{
NixInt n;
Value v;
ExprInt(NixInt n) : n(n) { mkInt(v, n); };
COMMON_METHODS
Value * maybeThunk(EvalState & state, Env & env);
};
struct ExprFloat : Expr
{
NixFloat nf;
Value v;
ExprFloat(NixFloat nf) : nf(nf) { mkFloat(v, nf); };
COMMON_METHODS
Value * maybeThunk(EvalState & state, Env & env);
};
struct ExprString : Expr
{
Symbol s;
Value v;
ExprString(const Symbol & s) : s(s) { mkString(v, s); };
COMMON_METHODS
Value * maybeThunk(EvalState & state, Env & env);
};
/* Temporary class used during parsing of indented strings. */
struct ExprIndStr : Expr
{
string s;
ExprIndStr(const string & s) : s(s) { };
};
struct ExprPath : Expr
{
string s;
Value v;
ExprPath(const string & s) : s(s) { v.mkPath(this->s.c_str()); };
COMMON_METHODS
Value * maybeThunk(EvalState & state, Env & env);
};
struct ExprVar : Expr
{
Pos pos;
Symbol name;
/* Whether the variable comes from an environment (e.g. a rec, let
or function argument) or from a "with". */
bool fromWith;
/* In the former case, the value is obtained by going `level'
levels up from the current environment and getting the
`displ'th value in that environment. In the latter case, the
value is obtained by getting the attribute named `name' from
the set stored in the environment that is `level' levels up
from the current one.*/
unsigned int level;
unsigned int displ;
ExprVar(const Symbol & name) : name(name) { };
ExprVar(const Pos & pos, const Symbol & name) : pos(pos), name(name) { };
COMMON_METHODS
Value * maybeThunk(EvalState & state, Env & env);
};
struct ExprSelect : Expr
{
Pos pos;
Expr * e, * def;
AttrPath attrPath;
ExprSelect(const Pos & pos, Expr * e, const AttrPath & attrPath, Expr * def) : pos(pos), e(e), def(def), attrPath(attrPath) { };
ExprSelect(const Pos & pos, Expr * e, const Symbol & name) : pos(pos), e(e), def(0) { attrPath.push_back(AttrName(name)); };
COMMON_METHODS
};
struct ExprOpHasAttr : Expr
{
Expr * e;
AttrPath attrPath;
ExprOpHasAttr(Expr * e, const AttrPath & attrPath) : e(e), attrPath(attrPath) { };
COMMON_METHODS
};
struct ExprAttrs : Expr
{
bool recursive;
Pos pos;
struct AttrDef {
bool inherited;
Expr * e;
Pos pos;
unsigned int displ; // displacement
AttrDef(Expr * e, const Pos & pos, bool inherited=false)
: inherited(inherited), e(e), pos(pos) { };
AttrDef() { };
};
typedef std::map<Symbol, AttrDef> AttrDefs;
AttrDefs attrs;
struct DynamicAttrDef {
Expr * nameExpr, * valueExpr;
Pos pos;
DynamicAttrDef(Expr * nameExpr, Expr * valueExpr, const Pos & pos)
: nameExpr(nameExpr), valueExpr(valueExpr), pos(pos) { };
};
typedef std::vector<DynamicAttrDef> DynamicAttrDefs;
DynamicAttrDefs dynamicAttrs;
ExprAttrs(const Pos &pos) : recursive(false), pos(pos) { };
ExprAttrs() : recursive(false), pos(noPos) { };
COMMON_METHODS
};
struct ExprList : Expr
{
std::vector<Expr *> elems;
ExprList() { };
COMMON_METHODS
};
struct Formal
{
Pos pos;
Symbol name;
Expr * def;
Formal(const Pos & pos, const Symbol & name, Expr * def) : pos(pos), name(name), def(def) { };
};
struct Formals
{
typedef std::list<Formal> Formals_;
Formals_ formals;
std::set<Symbol> argNames; // used during parsing
bool ellipsis;
};
struct ExprLambda : Expr
{
Pos pos;
Symbol name;
Symbol arg;
Formals * formals;
Expr * body;
ExprLambda(const Pos & pos, const Symbol & arg, Formals * formals, Expr * body)
: pos(pos), arg(arg), formals(formals), body(body)
{
if (!arg.empty() && formals && formals->argNames.find(arg) != formals->argNames.end())
throw ParseError({
.msg = hintfmt("duplicate formal function argument '%1%'", arg),
.errPos = pos
});
};
void setName(Symbol & name);
string showNamePos() const;
inline bool hasFormals() const { return formals != nullptr; }
COMMON_METHODS
};
struct ExprLet : Expr
{
ExprAttrs * attrs;
Expr * body;
ExprLet(ExprAttrs * attrs, Expr * body) : attrs(attrs), body(body) { };
COMMON_METHODS
};
struct ExprWith : Expr
{
Pos pos;
Expr * attrs, * body;
size_t prevWith;
ExprWith(const Pos & pos, Expr * attrs, Expr * body) : pos(pos), attrs(attrs), body(body) { };
COMMON_METHODS
};
struct ExprIf : Expr
{
Pos pos;
Expr * cond, * then, * else_;
ExprIf(const Pos & pos, Expr * cond, Expr * then, Expr * else_) : pos(pos), cond(cond), then(then), else_(else_) { };
COMMON_METHODS
};
struct ExprAssert : Expr
{
Pos pos;
Expr * cond, * body;
ExprAssert(const Pos & pos, Expr * cond, Expr * body) : pos(pos), cond(cond), body(body) { };
COMMON_METHODS
};
struct ExprOpNot : Expr
{
Expr * e;
ExprOpNot(Expr * e) : e(e) { };
COMMON_METHODS
};
#define MakeBinOp(name, s) \
struct name : Expr \
{ \
Pos pos; \
Expr * e1, * e2; \
name(Expr * e1, Expr * e2) : e1(e1), e2(e2) { }; \
name(const Pos & pos, Expr * e1, Expr * e2) : pos(pos), e1(e1), e2(e2) { }; \
void show(std::ostream & str) const \
{ \
str << "(" << *e1 << " " s " " << *e2 << ")"; \
} \
void bindVars(const StaticEnv & env) \
{ \
e1->bindVars(env); e2->bindVars(env); \
} \
void eval(EvalState & state, Env & env, Value & v); \
};
MakeBinOp(ExprApp, "")
MakeBinOp(ExprOpEq, "==")
MakeBinOp(ExprOpNEq, "!=")
MakeBinOp(ExprOpAnd, "&&")
MakeBinOp(ExprOpOr, "||")
MakeBinOp(ExprOpImpl, "->")
MakeBinOp(ExprOpUpdate, "//")
MakeBinOp(ExprOpConcatLists, "++")
struct ExprConcatStrings : Expr
{
Pos pos;
bool forceString;
vector<Expr *> * es;
ExprConcatStrings(const Pos & pos, bool forceString, vector<Expr *> * es)
: pos(pos), forceString(forceString), es(es) { };
COMMON_METHODS
};
struct ExprPos : Expr
{
Pos pos;
ExprPos(const Pos & pos) : pos(pos) { };
COMMON_METHODS
};
/* Static environments are used to map variable names onto (level,
displacement) pairs used to obtain the value of the variable at
runtime. */
struct StaticEnv
{
bool isWith;
const StaticEnv * up;
typedef std::map<Symbol, unsigned int> Vars;
Vars vars;
StaticEnv(bool isWith, const StaticEnv * up) : isWith(isWith), up(up) { };
};
}