diff options
Diffstat (limited to 'src/libexpr/eval.hh')
| -rw-r--r-- | src/libexpr/eval.hh | 324 |
1 files changed, 275 insertions, 49 deletions
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh index fed6d347266b..1a9862c29533 100644 --- a/src/libexpr/eval.hh +++ b/src/libexpr/eval.hh @@ -3,17 +3,165 @@ #include <map> -#include "aterm.hh" #include "nixexpr.hh" +#include "symbol-table.hh" namespace nix { class Hash; - +class EvalState; +struct Env; +struct Value; +struct Attr; + +typedef std::map<Symbol, Attr> Bindings; + + +typedef enum { + tInt = 1, + tBool, + tString, + tPath, + tNull, + tAttrs, + tList, + tThunk, + tApp, + tLambda, + tCopy, + tBlackhole, + tPrimOp, + tPrimOpApp, +} ValueType; + + +typedef void (* PrimOp) (EvalState & state, Value * * args, Value & v); + + +struct Value +{ + ValueType type; + union + { + int integer; + bool boolean; + + /* Strings in the evaluator carry a so-called `context' (the + ATermList) which is a list of strings representing store + paths. This is to allow users to write things like + + "--with-freetype2-library=" + freetype + "/lib" + + where `freetype' is a derivation (or a source to be copied + to the store). If we just concatenated the strings without + keeping track of the referenced store paths, then if the + string is used as a derivation attribute, the derivation + will not have the correct dependencies in its inputDrvs and + inputSrcs. + + The semantics of the context is as follows: when a string + with context C is used as a derivation attribute, then the + derivations in C will be added to the inputDrvs of the + derivation, and the other store paths in C will be added to + the inputSrcs of the derivations. + + For canonicity, the store paths should be in sorted order. */ + struct { + const char * s; + const char * * context; // must be in sorted order + } string; + + const char * path; + Bindings * attrs; + struct { + unsigned int length; + Value * * elems; + } list; + struct { + Env * env; + Expr * expr; + } thunk; + struct { + Value * left, * right; + } app; + struct { + Env * env; + ExprLambda * fun; + } lambda; + Value * val; + struct { + PrimOp fun; + char * name; + unsigned int arity; + } primOp; + struct { + Value * left, * right; + unsigned int argsLeft; + } primOpApp; + }; +}; + + +struct Env +{ + Env * up; + unsigned int prevWith; // nr of levels up to next `with' environment + Value values[0]; +}; + + +struct Attr +{ + Value value; + Pos * pos; + Attr() : pos(&noPos) { }; +}; + + +static inline void mkInt(Value & v, int n) +{ + v.type = tInt; + v.integer = n; +} + + +static inline void mkBool(Value & v, bool b) +{ + v.type = tBool; + v.boolean = b; +} + + +static inline void mkThunk(Value & v, Env & env, Expr * expr) +{ + v.type = tThunk; + v.thunk.env = &env; + v.thunk.expr = expr; +} + + +static inline void mkCopy(Value & v, Value & src) +{ + v.type = tCopy; + v.val = &src; +} + + +static inline void mkApp(Value & v, Value & left, Value & right) +{ + v.type = tApp; + v.app.left = &left; + v.app.right = &right; +} + + +void mkString(Value & v, const char * s); +void mkString(Value & v, const string & s, const PathSet & context = PathSet()); +void mkPath(Value & v, const char * s); + -typedef std::map<Path, PathSet> DrvRoots; typedef std::map<Path, Hash> DrvHashes; /* Cache for calls to addToStore(); maps source paths to the store @@ -22,75 +170,153 @@ typedef std::map<Path, Path> SrcToStore; struct EvalState; -/* Note: using a ATermVector is safe here, since when we call a primop - we also have an ATermList on the stack. */ -typedef Expr (* PrimOp) (EvalState &, const ATermVector & args); + +std::ostream & operator << (std::ostream & str, Value & v); -struct EvalState +class EvalState { - ATermMap normalForms; - ATermMap primOps; - DrvRoots drvRoots; +public: DrvHashes drvHashes; /* normalised derivation hashes */ - SrcToStore srcToStore; - unsigned int nrEvaluated; - unsigned int nrCached; + SymbolTable symbols; + + const Symbol sWith, sOutPath, sDrvPath, sType, sMeta, sName, sSystem; + +private: + SrcToStore srcToStore; bool allowUnsafeEquality; + std::map<Path, Expr *> parseTrees; + +public: + EvalState(); + ~EvalState(); + + /* Evaluate an expression read from the given file to normal + form. */ + void evalFile(const Path & path, Value & v); + + /* Evaluate an expression to normal form, storing the result in + value `v'. */ + void eval(Expr * e, Value & v); + void eval(Env & env, Expr * e, Value & v); + + /* Evaluation the expression, then verify that it has the expected + type. */ + bool evalBool(Env & env, Expr * e); + void evalAttrs(Env & env, Expr * e, Value & v); + + /* If `v' is a thunk, enter it and overwrite `v' with the result + of the evaluation of the thunk. If `v' is a delayed function + application, call the function and overwrite `v' with the + result. Otherwise, this is a no-op. */ + void forceValue(Value & v); + + /* Force a value, then recursively force list elements and + attributes. */ + void strictForceValue(Value & v); + + /* Force `v', and then verify that it has the expected type. */ + int forceInt(Value & v); + bool forceBool(Value & v); + void forceAttrs(Value & v); + void forceList(Value & v); + void forceFunction(Value & v); // either lambda or primop + string forceString(Value & v); + string forceString(Value & v, PathSet & context); + string forceStringNoCtx(Value & v); + + /* Return true iff the value `v' denotes a derivation (i.e. a + set with attribute `type = "derivation"'). */ + bool isDerivation(Value & v); + + /* String coercion. Converts strings, paths and derivations to a + string. If `coerceMore' is set, also converts nulls, integers, + booleans and lists to a string. If `copyToStore' is set, + referenced paths are copied to the Nix store as a side effect.q */ + string coerceToString(Value & v, PathSet & context, + bool coerceMore = false, bool copyToStore = true); + + /* Path coercion. Converts strings, paths and derivations to a + path. The result is guaranteed to be a canonicalised, absolute + path. Nothing is copied to the store. */ + Path coerceToPath(Value & v, PathSet & context); + +private: + + /* The base environment, containing the builtin functions and + values. */ + Env & baseEnv; + + unsigned int baseEnvDispl; + +public: + + /* The same, but used during parsing to resolve variables. */ + StaticEnv staticBaseEnv; // !!! should be private + +private: + + void createBaseEnv(); + + void addConstant(const string & name, Value & v); - void addPrimOps(); void addPrimOp(const string & name, unsigned int arity, PrimOp primOp); -}; + Value * lookupVar(Env * env, const VarRef & var); + + friend class ExprVar; + friend class ExprAttrs; + friend class ExprLet; -/* Evaluate an expression to normal form. */ -Expr evalExpr(EvalState & state, Expr e); +public: + + /* Do a deep equality test between two values. That is, list + elements and attributes are compared recursively. */ + bool eqValues(Value & v1, Value & v2); -/* Evaluate an expression read from the given file to normal form. */ -Expr evalFile(EvalState & state, const Path & path); + void callFunction(Value & fun, Value & arg, Value & v); -/* Evaluate an expression, and recursively evaluate list elements and - attributes. If `canonicalise' is true, we remove things like - position information and make sure that attribute sets are in - sorded order. */ -Expr strictEvalExpr(EvalState & state, Expr e); + /* Automatically call a function for which each argument has a + default value or has a binding in the `args' map. */ + void autoCallFunction(const Bindings & args, Value & fun, Value & res); + + /* Allocation primitives. */ + Value * allocValues(unsigned int count); + Env & allocEnv(unsigned int size); -/* Specific results. */ -string evalString(EvalState & state, Expr e, PathSet & context); -string evalStringNoCtx(EvalState & state, Expr e); -int evalInt(EvalState & state, Expr e); -bool evalBool(EvalState & state, Expr e); -ATermList evalList(EvalState & state, Expr e); + void mkList(Value & v, unsigned int length); + void mkAttrs(Value & v); + void mkThunk_(Value & v, Expr * expr); + + void cloneAttrs(Value & src, Value & dst); -/* Flatten nested lists into a single list (or expand a singleton into - a list). */ -ATermList flattenList(EvalState & state, Expr e); + /* Print statistics. */ + void printStats(); -/* String coercion. Converts strings, paths and derivations to a - string. If `coerceMore' is set, also converts nulls, integers, - booleans and lists to a string. */ -string coerceToString(EvalState & state, Expr e, PathSet & context, - bool coerceMore = false, bool copyToStore = true); +private: + + unsigned long nrEnvs; + unsigned long nrValuesInEnvs; + unsigned long nrValues; + unsigned long nrListElems; + unsigned long nrEvaluated; + unsigned int recursionDepth; + unsigned int maxRecursionDepth; + char * deepestStack; /* for measuring stack usage */ + + friend class RecursionCounter; +}; -/* Path coercion. Converts strings, paths and derivations to a path. - The result is guaranteed to be an canonicalised, absolute path. - Nothing is copied to the store. */ -Path coerceToPath(EvalState & state, Expr e, PathSet & context); -/* Automatically call a function for which each argument has a default - value or has a binding in the `args' map. Note: result is a call, - not a normal form; it should be evaluated by calling evalExpr(). */ -Expr autoCallFunction(Expr e, const ATermMap & args); +/* Return a string representing the type of the value `v'. */ +string showType(const Value & v); -/* Print statistics. */ -void printEvalStats(EvalState & state); - } |