forked from lix-project/lix
153 lines
3.1 KiB
C++
153 lines
3.1 KiB
C++
#pragma once
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#include "symbol-table.hh"
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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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tList,
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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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} ValueType;
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struct 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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struct Symbol;
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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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int integer;
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bool boolean;
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/* Strings in the evaluator carry a so-called `context' (the
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ATermList) which is a list of strings representing store
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paths. This is to 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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unsigned int length;
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Value * * elems;
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} list;
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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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};
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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.right = 0;
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}
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static inline void mkInt(Value & v, int 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 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 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 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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}
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