%glr-parser %pure-parser %locations %error-verbose %defines /* %no-lines */ %parse-param { yyscan_t scanner } %parse-param { ParseData * data } %lex-param { yyscan_t scanner } %lex-param { ParseData * data } %code requires { #ifndef BISON_HEADER #define BISON_HEADER #include "util.hh" #include "nixexpr.hh" namespace nix { struct ParseData { SymbolTable & symbols; Expr * result; Path basePath; Path path; string error; Symbol sLetBody; ParseData(SymbolTable & symbols) : symbols(symbols) , sLetBody(symbols.create("<let-body>")) { }; }; } #define YY_DECL int yylex \ (YYSTYPE * yylval_param, YYLTYPE * yylloc_param, yyscan_t yyscanner, nix::ParseData * data) #endif } %{ #include "parser-tab.hh" #include "lexer-tab.hh" #define YYSTYPE YYSTYPE // workaround a bug in Bison 2.4 #include <stdio.h> #include <stdlib.h> #include <string.h> YY_DECL; using namespace nix; namespace nix { static void dupAttr(const AttrPath & attrPath, const Pos & pos, const Pos & prevPos) { throw ParseError(format("attribute `%1%' at %2% already defined at %3%") % showAttrPath(attrPath) % pos % prevPos); } static void dupAttr(Symbol attr, const Pos & pos, const Pos & prevPos) { AttrPath attrPath; attrPath.push_back(attr); throw ParseError(format("attribute `%1%' at %2% already defined at %3%") % showAttrPath(attrPath) % pos % prevPos); } static void addAttr(ExprAttrs * attrs, AttrPath & attrPath, Expr * e, const Pos & pos) { unsigned int n = 0; foreach (AttrPath::const_iterator, i, attrPath) { n++; ExprAttrs::AttrDefs::iterator j = attrs->attrs.find(*i); if (j != attrs->attrs.end()) { if (!j->second.inherited) { ExprAttrs * attrs2 = dynamic_cast<ExprAttrs *>(j->second.e); if (!attrs2 || n == attrPath.size()) dupAttr(attrPath, pos, j->second.pos); attrs = attrs2; } else dupAttr(attrPath, pos, j->second.pos); } else { if (n == attrPath.size()) attrs->attrs[*i] = ExprAttrs::AttrDef(e, pos); else { ExprAttrs * nested = new ExprAttrs; attrs->attrs[*i] = ExprAttrs::AttrDef(nested, pos); attrs = nested; } } } } static void addFormal(const Pos & pos, Formals * formals, const Formal & formal) { if (formals->argNames.find(formal.name) != formals->argNames.end()) throw ParseError(format("duplicate formal function argument `%1%' at %2%") % formal.name % pos); formals->formals.push_front(formal); formals->argNames.insert(formal.name); } static Expr * stripIndentation(SymbolTable & symbols, vector<Expr *> & es) { if (es.empty()) return new ExprString(symbols.create("")); /* Figure out the minimum indentation. Note that by design whitespace-only final lines are not taken into account. (So the " " in "\n ''" is ignored, but the " " in "\n foo''" is.) */ bool atStartOfLine = true; /* = seen only whitespace in the current line */ unsigned int minIndent = 1000000; unsigned int curIndent = 0; foreach (vector<Expr *>::iterator, i, es) { ExprIndStr * e = dynamic_cast<ExprIndStr *>(*i); if (!e) { /* Anti-quotations end the current start-of-line whitespace. */ if (atStartOfLine) { atStartOfLine = false; if (curIndent < minIndent) minIndent = curIndent; } continue; } for (unsigned int j = 0; j < e->s.size(); ++j) { if (atStartOfLine) { if (e->s[j] == ' ') curIndent++; else if (e->s[j] == '\n') { /* Empty line, doesn't influence minimum indentation. */ curIndent = 0; } else { atStartOfLine = false; if (curIndent < minIndent) minIndent = curIndent; } } else if (e->s[j] == '\n') { atStartOfLine = true; curIndent = 0; } } } /* Strip spaces from each line. */ vector<Expr *> * es2 = new vector<Expr *>; atStartOfLine = true; unsigned int curDropped = 0; unsigned int n = es.size(); for (vector<Expr *>::iterator i = es.begin(); i != es.end(); ++i, --n) { ExprIndStr * e = dynamic_cast<ExprIndStr *>(*i); if (!e) { atStartOfLine = false; curDropped = 0; es2->push_back(*i); continue; } string s2; for (unsigned int j = 0; j < e->s.size(); ++j) { if (atStartOfLine) { if (e->s[j] == ' ') { if (curDropped++ >= minIndent) s2 += e->s[j]; } else if (e->s[j] == '\n') { curDropped = 0; s2 += e->s[j]; } else { atStartOfLine = false; curDropped = 0; s2 += e->s[j]; } } else { s2 += e->s[j]; if (e->s[j] == '\n') atStartOfLine = true; } } /* Remove the last line if it is empty and consists only of spaces. */ if (n == 1) { string::size_type p = s2.find_last_of('\n'); if (p != string::npos && s2.find_first_not_of(' ', p + 1) == string::npos) s2 = string(s2, 0, p + 1); } es2->push_back(new ExprString(symbols.create(s2))); } return new ExprConcatStrings(es2); } void backToString(yyscan_t scanner); void backToIndString(yyscan_t scanner); static Pos makeCurPos(const YYLTYPE & loc, ParseData * data) { return Pos(data->path, loc.first_line, loc.first_column); } #define CUR_POS makeCurPos(*yylocp, data) } void yyerror(YYLTYPE * loc, yyscan_t scanner, ParseData * data, const char * error) { data->error = (format("%1%, at %2%") % error % makeCurPos(*loc, data)).str(); } %} %union { // !!! We're probably leaking stuff here. nix::Expr * e; nix::ExprList * list; nix::ExprAttrs * attrs; nix::Formals * formals; nix::Formal * formal; int n; char * id; // !!! -> Symbol char * path; char * uri; std::vector<nix::Symbol> * attrNames; std::vector<nix::Expr *> * string_parts; } %type <e> start expr expr_function expr_if expr_op %type <e> expr_app expr_select expr_simple %type <list> expr_list %type <attrs> binds %type <formals> formals %type <formal> formal %type <attrNames> attrs attrpath %type <string_parts> string_parts ind_string_parts %type <id> attr %token <id> ID ATTRPATH %token <e> STR IND_STR %token <n> INT %token <path> PATH %token <uri> URI %token IF THEN ELSE ASSERT WITH LET IN REC INHERIT EQ NEQ AND OR IMPL OR_KW %token DOLLAR_CURLY /* == ${ */ %token IND_STRING_OPEN IND_STRING_CLOSE %token ELLIPSIS %nonassoc IMPL %left OR %left AND %nonassoc EQ NEQ %right UPDATE %left NEG %left '+' %right CONCAT %nonassoc '?' %nonassoc '~' %% start: expr { data->result = $1; }; expr: expr_function; expr_function : ID ':' expr_function { $$ = new ExprLambda(CUR_POS, data->symbols.create($1), false, 0, $3); } | '{' formals '}' ':' expr_function { $$ = new ExprLambda(CUR_POS, data->symbols.create(""), true, $2, $5); } | '{' formals '}' '@' ID ':' expr_function { $$ = new ExprLambda(CUR_POS, data->symbols.create($5), true, $2, $7); } | ID '@' '{' formals '}' ':' expr_function { $$ = new ExprLambda(CUR_POS, data->symbols.create($1), true, $4, $7); } | ASSERT expr ';' expr_function { $$ = new ExprAssert(CUR_POS, $2, $4); } | WITH expr ';' expr_function { $$ = new ExprWith(CUR_POS, $2, $4); } | LET binds IN expr_function { $$ = new ExprLet($2, $4); } | expr_if ; expr_if : IF expr THEN expr ELSE expr { $$ = new ExprIf($2, $4, $6); } | expr_op ; expr_op : '!' expr_op %prec NEG { $$ = new ExprOpNot($2); } | expr_op EQ expr_op { $$ = new ExprOpEq($1, $3); } | expr_op NEQ expr_op { $$ = new ExprOpNEq($1, $3); } | expr_op AND expr_op { $$ = new ExprOpAnd($1, $3); } | expr_op OR expr_op { $$ = new ExprOpOr($1, $3); } | expr_op IMPL expr_op { $$ = new ExprOpImpl($1, $3); } | expr_op UPDATE expr_op { $$ = new ExprOpUpdate($1, $3); } | expr_op '?' attrpath { $$ = new ExprOpHasAttr($1, *$3); } | expr_op '+' expr_op { vector<Expr *> * l = new vector<Expr *>; l->push_back($1); l->push_back($3); $$ = new ExprConcatStrings(l); } | expr_op CONCAT expr_op { $$ = new ExprOpConcatLists($1, $3); } | expr_app ; expr_app : expr_app expr_select { $$ = new ExprApp($1, $2); } | expr_select { $$ = $1; } ; expr_select : expr_simple '.' attrpath { $$ = new ExprSelect($1, *$3, 0); } | expr_simple '.' attrpath OR_KW expr_select { $$ = new ExprSelect($1, *$3, $5); } | /* Backwards compatibility: because Nixpkgs has a rarely used function named ‘or’, allow stuff like ‘map or [...]’. */ expr_simple OR_KW { $$ = new ExprApp($1, new ExprVar(data->symbols.create("or"))); } | expr_simple { $$ = $1; } ; expr_simple : ID { $$ = new ExprVar(data->symbols.create($1)); } | INT { $$ = new ExprInt($1); } | '"' string_parts '"' { /* For efficiency, and to simplify parse trees a bit. */ if ($2->empty()) $$ = new ExprString(data->symbols.create("")); else if ($2->size() == 1) $$ = $2->front(); else $$ = new ExprConcatStrings($2); } | IND_STRING_OPEN ind_string_parts IND_STRING_CLOSE { $$ = stripIndentation(data->symbols, *$2); } | PATH { $$ = new ExprPath(absPath($1, data->basePath)); } | URI { $$ = new ExprString(data->symbols.create($1)); } | '(' expr ')' { $$ = $2; } /* Let expressions `let {..., body = ...}' are just desugared into `(rec {..., body = ...}).body'. */ | LET '{' binds '}' { $3->recursive = true; $$ = new ExprSelect($3, data->symbols.create("body")); } | REC '{' binds '}' { $3->recursive = true; $$ = $3; } | '{' binds '}' { $$ = $2; } | '[' expr_list ']' { $$ = $2; } ; string_parts : string_parts STR { $$ = $1; $1->push_back($2); } | string_parts DOLLAR_CURLY expr '}' { backToString(scanner); $$ = $1; $1->push_back($3); } | { $$ = new vector<Expr *>; } ; ind_string_parts : ind_string_parts IND_STR { $$ = $1; $1->push_back($2); } | ind_string_parts DOLLAR_CURLY expr '}' { backToIndString(scanner); $$ = $1; $1->push_back($3); } | { $$ = new vector<Expr *>; } ; binds : binds attrpath '=' expr ';' { $$ = $1; addAttr($$, *$2, $4, makeCurPos(@2, data)); } | binds INHERIT attrs ';' { $$ = $1; foreach (AttrPath::iterator, i, *$3) { if ($$->attrs.find(*i) != $$->attrs.end()) dupAttr(*i, makeCurPos(@3, data), $$->attrs[*i].pos); Pos pos = makeCurPos(@3, data); $$->attrs[*i] = ExprAttrs::AttrDef(*i, pos); } } | binds INHERIT '(' expr ')' attrs ';' { $$ = $1; /* !!! Should ensure sharing of the expression in $4. */ foreach (vector<Symbol>::iterator, i, *$6) { if ($$->attrs.find(*i) != $$->attrs.end()) dupAttr(*i, makeCurPos(@6, data), $$->attrs[*i].pos); $$->attrs[*i] = ExprAttrs::AttrDef(new ExprSelect($4, *i), makeCurPos(@6, data)); } } | { $$ = new ExprAttrs; } ; attrs : attrs attr { $$ = $1; $1->push_back(data->symbols.create($2)); /* !!! dangerous */ } | { $$ = new vector<Symbol>; } ; attrpath : attrpath '.' attr { $$ = $1; $1->push_back(data->symbols.create($3)); } | attr { $$ = new vector<Symbol>; $$->push_back(data->symbols.create($1)); } ; attr : ID { $$ = $1; } | OR_KW { $$ = "or"; } | '"' STR '"' { $$ = strdup(((string) ((ExprString *) $2)->s).c_str()); delete $2; } ; expr_list : expr_list expr_select { $$ = $1; $1->elems.push_back($2); /* !!! dangerous */ } | { $$ = new ExprList; } ; formals : formal ',' formals { $$ = $3; addFormal(CUR_POS, $$, *$1); } | formal { $$ = new Formals; addFormal(CUR_POS, $$, *$1); $$->ellipsis = false; } | { $$ = new Formals; $$->ellipsis = false; } | ELLIPSIS { $$ = new Formals; $$->ellipsis = true; } ; formal : ID { $$ = new Formal(data->symbols.create($1), 0); } | ID '?' expr { $$ = new Formal(data->symbols.create($1), $3); } ; %% #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> #include <eval.hh> namespace nix { static Expr * parse(EvalState & state, const char * text, const Path & path, const Path & basePath) { yyscan_t scanner; ParseData data(state.symbols); data.basePath = basePath; data.path = path; yylex_init(&scanner); yy_scan_string(text, scanner); int res = yyparse(scanner, &data); yylex_destroy(scanner); if (res) throw ParseError(data.error); try { data.result->bindVars(state.staticBaseEnv); } catch (Error & e) { throw ParseError(format("%1%, in `%2%'") % e.msg() % path); } return data.result; } Expr * parseExprFromFile(EvalState & state, Path path) { assert(path[0] == '/'); /* If `path' is a symlink, follow it. This is so that relative path references work. */ struct stat st; while (true) { if (lstat(path.c_str(), &st)) throw SysError(format("getting status of `%1%'") % path); if (!S_ISLNK(st.st_mode)) break; path = absPath(readLink(path), dirOf(path)); } /* If `path' refers to a directory, append `/default.nix'. */ if (S_ISDIR(st.st_mode)) path = canonPath(path + "/default.nix"); /* Read and parse the input file. */ return parse(state, readFile(path).c_str(), path, dirOf(path)); } Expr * parseExprFromString(EvalState & state, const string & s, const Path & basePath) { return parse(state, s.c_str(), "(string)", basePath); } }