mirror of
https://github.com/NixOS/nix
synced 2025-06-27 21:01:16 +02:00
* Use a symbol table to represent identifiers and attribute names
efficiently. The symbol table ensures that there is only one copy of each symbol, thus allowing symbols to be compared efficiently using a pointer equality test.
This commit is contained in:
Eelco Dolstra
parent
10e8b1fd15
commit
ac1e8f40d4
15 changed files with 228 additions and 101 deletions
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@ -37,17 +37,23 @@ namespace nix {
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struct ParseData
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{
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SymbolTable & symbols;
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Expr * result;
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Path basePath;
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Path path;
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string error;
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Symbol sLetBody;
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ParseData(SymbolTable & symbols)
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: symbols(symbols)
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, sLetBody(symbols.create("<let-body>"))
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{ };
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};
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static string showAttrPath(const vector<string> & attrPath)
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static string showAttrPath(const vector<Symbol> & attrPath)
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{
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string s;
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foreach (vector<string>::const_iterator, i, attrPath) {
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foreach (vector<Symbol>::const_iterator, i, attrPath) {
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if (!s.empty()) s += '.';
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s += *i;
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}
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@ -55,10 +61,11 @@ static string showAttrPath(const vector<string> & attrPath)
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}
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static void addAttr(ExprAttrs * attrs, const vector<string> & attrPath, Expr * e, const Pos & pos)
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static void addAttr(ExprAttrs * attrs, const vector<Symbol> & attrPath,
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Expr * e, const Pos & pos)
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{
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unsigned int n = 0;
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foreach (vector<string>::const_iterator, i, attrPath) {
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foreach (vector<Symbol>::const_iterator, i, attrPath) {
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n++;
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if (attrs->attrs[*i]) {
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ExprAttrs * attrs2 = dynamic_cast<ExprAttrs *>(attrs->attrs[*i]);
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@ -243,10 +250,10 @@ void yyerror(YYLTYPE * loc, yyscan_t scanner, ParseData * data, const char * err
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nix::Formals * formals;
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nix::Formal * formal;
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int n;
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char * id;
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char * id; // !!! -> Symbol
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char * path;
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char * uri;
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std::vector<std::string> * ids;
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std::vector<nix::Symbol> * ids;
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std::vector<nix::Expr *> * string_parts;
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}
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@ -287,19 +294,19 @@ expr: expr_function;
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expr_function
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: ID ':' expr_function
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{ $$ = new ExprLambda(CUR_POS, $1, false, 0, $3); /* checkPatternVars(CUR_POS, $1); $$ = makeFunction($1, $3, CUR_POS); */ }
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{ $$ = new ExprLambda(CUR_POS, data->symbols.create($1), false, 0, $3); /* checkPatternVars(CUR_POS, $1); */ }
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| '{' formals '}' ':' expr_function
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{ $$ = new ExprLambda(CUR_POS, "", true, $2, $5); }
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{ $$ = new ExprLambda(CUR_POS, data->symbols.create(""), true, $2, $5); }
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| '{' formals '}' '@' ID ':' expr_function
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{ $$ = new ExprLambda(CUR_POS, $5, true, $2, $7); }
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{ $$ = new ExprLambda(CUR_POS, data->symbols.create($5), true, $2, $7); }
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| ID '@' '{' formals '}' ':' expr_function
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{ $$ = new ExprLambda(CUR_POS, $1, true, $4, $7); }
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{ $$ = new ExprLambda(CUR_POS, data->symbols.create($1), true, $4, $7); }
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| ASSERT expr ';' expr_function
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{ $$ = new ExprAssert(CUR_POS, $2, $4); }
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| WITH expr ';' expr_function
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{ $$ = new ExprWith(CUR_POS, $2, $4); }
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| LET binds IN expr_function
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{ $2->attrs["<let-body>"] = $4; $2->recursive = true; $$ = new ExprSelect($2, "<let-body>"); }
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{ $2->attrs[data->sLetBody] = $4; $2->recursive = true; $$ = new ExprSelect($2, data->sLetBody); }
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| expr_if
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;
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@ -316,7 +323,7 @@ expr_op
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| expr_op OR expr_op { $$ = new ExprOpOr($1, $3); }
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| expr_op IMPL expr_op { $$ = new ExprOpImpl($1, $3); }
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| expr_op UPDATE expr_op { $$ = new ExprOpUpdate($1, $3); }
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| expr_op '?' ID { $$ = new ExprOpHasAttr($1, $3); }
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| expr_op '?' ID { $$ = new ExprOpHasAttr($1, data->symbols.create($3)); }
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| expr_op '+' expr_op
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{ vector<Expr *> * l = new vector<Expr *>;
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l->push_back($1);
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@ -335,12 +342,12 @@ expr_app
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expr_select
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: expr_select '.' ID
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{ $$ = new ExprSelect($1, $3); }
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{ $$ = new ExprSelect($1, data->symbols.create($3)); }
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| expr_simple { $$ = $1; }
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;
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expr_simple
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: ID { $$ = new ExprVar($1); }
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: ID { $$ = new ExprVar(data->symbols.create($1)); }
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| INT { $$ = new ExprInt($1); }
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| '"' string_parts '"' {
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/* For efficiency, and to simplify parse trees a bit. */
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@ -357,7 +364,7 @@ expr_simple
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/* Let expressions `let {..., body = ...}' are just desugared
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into `(rec {..., body = ...}).body'. */
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| LET '{' binds '}'
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{ $3->recursive = true; $$ = new ExprSelect($3, "body"); }
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{ $3->recursive = true; $$ = new ExprSelect($3, data->symbols.create("body")); }
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| REC '{' binds '}'
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{ $3->recursive = true; $$ = $3; }
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| '{' binds '}'
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@ -381,26 +388,26 @@ binds
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: binds attrpath '=' expr ';' { $$ = $1; addAttr($$, *$2, $4, CUR_POS); }
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| binds INHERIT ids ';'
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{ $$ = $1;
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foreach (vector<string>::iterator, i, *$3)
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foreach (vector<Symbol>::iterator, i, *$3)
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$$->inherited.push_back(*i);
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}
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| binds INHERIT '(' expr ')' ids ';'
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{ $$ = $1;
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/* !!! Should ensure sharing of the expression in $4. */
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foreach (vector<string>::iterator, i, *$6)
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foreach (vector<Symbol>::iterator, i, *$6)
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$$->attrs[*i] = new ExprSelect($4, *i);
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}
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| { $$ = new ExprAttrs; }
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;
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ids
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: ids ID { $$ = $1; $1->push_back($2); /* !!! dangerous */ }
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| { $$ = new vector<string>; }
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: ids ID { $$ = $1; $1->push_back(data->symbols.create($2)); /* !!! dangerous */ }
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| { $$ = new vector<Symbol>; }
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;
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attrpath
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: attrpath '.' ID { $$ = $1; $1->push_back($3); }
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| ID { $$ = new vector<string>; $$->push_back($1); }
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: attrpath '.' ID { $$ = $1; $1->push_back(data->symbols.create($3)); }
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| ID { $$ = new vector<Symbol>; $$->push_back(data->symbols.create($1)); }
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;
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expr_list
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@ -420,8 +427,8 @@ formals
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;
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formal
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: ID { $$ = new Formal($1, 0); }
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| ID '?' expr { $$ = new Formal($1, $3); }
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: ID { $$ = new Formal(data->symbols.create($1), 0); }
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| ID '?' expr { $$ = new Formal(data->symbols.create($1), $3); }
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;
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%%
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@ -432,14 +439,17 @@ formal
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#include <fcntl.h>
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#include <unistd.h>
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#include <eval.hh>
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namespace nix {
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static Expr * parse(const char * text, const Path & path, const Path & basePath)
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static Expr * parse(EvalState & state, const char * text,
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const Path & path, const Path & basePath)
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{
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yyscan_t scanner;
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ParseData data;
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ParseData data(state.symbols);
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data.basePath = basePath;
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data.path = path;
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@ -460,7 +470,7 @@ static Expr * parse(const char * text, const Path & path, const Path & basePath)
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}
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Expr * parseExprFromFile(Path path)
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Expr * parseExprFromFile(EvalState & state, Path path)
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{
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assert(path[0] == '/');
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@ -481,13 +491,14 @@ Expr * parseExprFromFile(Path path)
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path = canonPath(path + "/default.nix");
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/* Read and parse the input file. */
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return parse(readFile(path).c_str(), path, dirOf(path));
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return parse(state, readFile(path).c_str(), path, dirOf(path));
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}
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Expr * parseExprFromString(const string & s, const Path & basePath)
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Expr * parseExprFromString(EvalState & state,
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const string & s, const Path & basePath)
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{
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return parse(s.c_str(), "(string)", basePath);
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return parse(state, s.c_str(), "(string)", basePath);
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}
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