forked from lix-project/lix
5f18cd2e84
Wacky string coercion semantics caused expressions like
exec = "${./my-script} params...";
to evaluate to a path (‘/path/my-script params’), because
anti-quotations are desuged to string concatenation:
exec = ./my-script + " params...";
By constrast, adding a space at the start would yield a string as
expected:
exec = " ${./my-script} params...";
Now the first example also evaluates to a string.
573 lines
16 KiB
Plaintext
573 lines
16 KiB
Plaintext
%glr-parser
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%pure-parser
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%locations
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%error-verbose
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%defines
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/* %no-lines */
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%parse-param { yyscan_t scanner }
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%parse-param { ParseData * data }
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%lex-param { yyscan_t scanner }
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%lex-param { ParseData * data }
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%expect 1
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%expect-rr 1
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%code requires {
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#ifndef BISON_HEADER
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#define BISON_HEADER
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#include "util.hh"
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#include "nixexpr.hh"
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#include "eval.hh"
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namespace nix {
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struct ParseData
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{
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EvalState & state;
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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(EvalState & state)
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: state(state)
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, symbols(state.symbols)
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, sLetBody(symbols.create("<let-body>"))
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{ };
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};
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}
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#define YY_DECL int yylex \
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(YYSTYPE * yylval_param, YYLTYPE * yylloc_param, yyscan_t yyscanner, nix::ParseData * data)
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#endif
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}
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%{
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#include "parser-tab.hh"
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#include "lexer-tab.hh"
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#define YYSTYPE YYSTYPE // workaround a bug in Bison 2.4
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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YY_DECL;
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using namespace nix;
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namespace nix {
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static void dupAttr(const AttrPath & attrPath, const Pos & pos, const Pos & prevPos)
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{
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throw ParseError(format("attribute `%1%' at %2% already defined at %3%")
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% showAttrPath(attrPath) % pos % prevPos);
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}
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static void dupAttr(Symbol attr, const Pos & pos, const Pos & prevPos)
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{
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AttrPath attrPath; attrPath.push_back(attr);
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throw ParseError(format("attribute `%1%' at %2% already defined at %3%")
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% showAttrPath(attrPath) % pos % prevPos);
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}
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static void addAttr(ExprAttrs * attrs, AttrPath & 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 (AttrPath::const_iterator, i, attrPath) {
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n++;
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ExprAttrs::AttrDefs::iterator j = attrs->attrs.find(*i);
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if (j != attrs->attrs.end()) {
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if (!j->second.inherited) {
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ExprAttrs * attrs2 = dynamic_cast<ExprAttrs *>(j->second.e);
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if (!attrs2 || n == attrPath.size()) dupAttr(attrPath, pos, j->second.pos);
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attrs = attrs2;
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} else
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dupAttr(attrPath, pos, j->second.pos);
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} else {
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if (n == attrPath.size())
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attrs->attrs[*i] = ExprAttrs::AttrDef(e, pos);
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else {
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ExprAttrs * nested = new ExprAttrs;
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attrs->attrs[*i] = ExprAttrs::AttrDef(nested, pos);
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attrs = nested;
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}
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}
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}
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}
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static void addFormal(const Pos & pos, Formals * formals, const Formal & formal)
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{
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if (formals->argNames.find(formal.name) != formals->argNames.end())
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throw ParseError(format("duplicate formal function argument `%1%' at %2%")
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% formal.name % pos);
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formals->formals.push_front(formal);
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formals->argNames.insert(formal.name);
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}
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static Expr * stripIndentation(SymbolTable & symbols, vector<Expr *> & es)
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{
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if (es.empty()) return new ExprString(symbols.create(""));
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/* Figure out the minimum indentation. Note that by design
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whitespace-only final lines are not taken into account. (So
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the " " in "\n ''" is ignored, but the " " in "\n foo''" is.) */
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bool atStartOfLine = true; /* = seen only whitespace in the current line */
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unsigned int minIndent = 1000000;
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unsigned int curIndent = 0;
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foreach (vector<Expr *>::iterator, i, es) {
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ExprIndStr * e = dynamic_cast<ExprIndStr *>(*i);
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if (!e) {
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/* Anti-quotations end the current start-of-line whitespace. */
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if (atStartOfLine) {
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atStartOfLine = false;
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if (curIndent < minIndent) minIndent = curIndent;
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}
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continue;
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}
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for (unsigned int j = 0; j < e->s.size(); ++j) {
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if (atStartOfLine) {
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if (e->s[j] == ' ')
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curIndent++;
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else if (e->s[j] == '\n') {
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/* Empty line, doesn't influence minimum
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indentation. */
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curIndent = 0;
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} else {
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atStartOfLine = false;
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if (curIndent < minIndent) minIndent = curIndent;
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}
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} else if (e->s[j] == '\n') {
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atStartOfLine = true;
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curIndent = 0;
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}
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}
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}
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/* Strip spaces from each line. */
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vector<Expr *> * es2 = new vector<Expr *>;
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atStartOfLine = true;
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unsigned int curDropped = 0;
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unsigned int n = es.size();
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for (vector<Expr *>::iterator i = es.begin(); i != es.end(); ++i, --n) {
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ExprIndStr * e = dynamic_cast<ExprIndStr *>(*i);
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if (!e) {
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atStartOfLine = false;
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curDropped = 0;
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es2->push_back(*i);
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continue;
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}
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string s2;
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for (unsigned int j = 0; j < e->s.size(); ++j) {
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if (atStartOfLine) {
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if (e->s[j] == ' ') {
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if (curDropped++ >= minIndent)
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s2 += e->s[j];
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}
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else if (e->s[j] == '\n') {
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curDropped = 0;
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s2 += e->s[j];
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} else {
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atStartOfLine = false;
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curDropped = 0;
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s2 += e->s[j];
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}
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} else {
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s2 += e->s[j];
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if (e->s[j] == '\n') atStartOfLine = true;
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}
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}
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/* Remove the last line if it is empty and consists only of
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spaces. */
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if (n == 1) {
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string::size_type p = s2.find_last_of('\n');
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if (p != string::npos && s2.find_first_not_of(' ', p + 1) == string::npos)
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s2 = string(s2, 0, p + 1);
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}
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es2->push_back(new ExprString(symbols.create(s2)));
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}
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return es2->size() == 1 ? (*es2)[0] : new ExprConcatStrings(true, es2);
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}
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void backToString(yyscan_t scanner);
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void backToIndString(yyscan_t scanner);
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static Pos makeCurPos(const YYLTYPE & loc, ParseData * data)
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{
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return Pos(data->path, loc.first_line, loc.first_column);
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}
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#define CUR_POS makeCurPos(*yylocp, data)
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}
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void yyerror(YYLTYPE * loc, yyscan_t scanner, ParseData * data, const char * error)
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{
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data->error = (format("%1%, at %2%")
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% error % makeCurPos(*loc, data)).str();
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}
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%}
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%union {
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// !!! We're probably leaking stuff here.
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nix::Expr * e;
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nix::ExprList * list;
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nix::ExprAttrs * attrs;
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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; // !!! -> Symbol
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char * path;
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char * uri;
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std::vector<nix::Symbol> * attrNames;
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std::vector<nix::Expr *> * string_parts;
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}
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%type <e> start expr expr_function expr_if expr_op
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%type <e> expr_app expr_select expr_simple
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%type <list> expr_list
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%type <attrs> binds
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%type <formals> formals
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%type <formal> formal
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%type <attrNames> attrs attrpath
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%type <string_parts> string_parts ind_string_parts
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%type <id> attr
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%token <id> ID ATTRPATH
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%token <e> STR IND_STR
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%token <n> INT
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%token <path> PATH SPATH
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%token <uri> URI
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%token IF THEN ELSE ASSERT WITH LET IN REC INHERIT EQ NEQ AND OR IMPL OR_KW
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%token DOLLAR_CURLY /* == ${ */
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%token IND_STRING_OPEN IND_STRING_CLOSE
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%token ELLIPSIS
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%nonassoc IMPL
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%left OR
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%left AND
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%nonassoc EQ NEQ
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%right UPDATE
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%left NEG
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%left '+'
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%right CONCAT
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%nonassoc '?'
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%nonassoc '~'
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%%
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start: expr { data->result = $1; };
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expr: expr_function;
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expr_function
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: ID ':' expr_function
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{ $$ = new ExprLambda(CUR_POS, data->symbols.create($1), false, 0, $3); }
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| '{' formals '}' ':' expr_function
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{ $$ = new ExprLambda(CUR_POS, data->symbols.create(""), true, $2, $5); }
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| '{' formals '}' '@' ID ':' expr_function
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{ $$ = new ExprLambda(CUR_POS, data->symbols.create($5), true, $2, $7); }
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| ID '@' '{' formals '}' ':' expr_function
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{ $$ = 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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{ $$ = new ExprLet($2, $4); }
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| expr_if
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;
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expr_if
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: IF expr THEN expr ELSE expr { $$ = new ExprIf($2, $4, $6); }
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| expr_op
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;
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expr_op
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: '!' expr_op %prec NEG { $$ = new ExprOpNot($2); }
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| expr_op EQ expr_op { $$ = new ExprOpEq($1, $3); }
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| expr_op NEQ expr_op { $$ = new ExprOpNEq($1, $3); }
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| expr_op AND expr_op { $$ = new ExprOpAnd($1, $3); }
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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 { $$ = new ExprOpUpdate($1, $3); }
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| expr_op '?' attrpath { $$ = new ExprOpHasAttr($1, *$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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l->push_back($3);
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$$ = new ExprConcatStrings(false, l);
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}
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| expr_op CONCAT expr_op { $$ = new ExprOpConcatLists($1, $3); }
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| expr_app
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;
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expr_app
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: expr_app expr_select
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{ $$ = new ExprApp($1, $2); }
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| expr_select { $$ = $1; }
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;
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expr_select
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: expr_simple '.' attrpath
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{ $$ = new ExprSelect($1, *$3, 0); }
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| expr_simple '.' attrpath OR_KW expr_select
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{ $$ = new ExprSelect($1, *$3, $5); }
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| /* Backwards compatibility: because Nixpkgs has a rarely used
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function named ‘or’, allow stuff like ‘map or [...]’. */
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expr_simple OR_KW
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{ $$ = new ExprApp($1, new ExprVar(data->symbols.create("or"))); }
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| expr_simple { $$ = $1; }
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;
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expr_simple
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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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if ($2->empty()) $$ = new ExprString(data->symbols.create(""));
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else if ($2->size() == 1) $$ = $2->front();
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else $$ = new ExprConcatStrings(true, $2);
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}
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| IND_STRING_OPEN ind_string_parts IND_STRING_CLOSE {
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$$ = stripIndentation(data->symbols, *$2);
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}
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| PATH { $$ = new ExprPath(absPath($1, data->basePath)); }
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| SPATH {
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string path($1 + 1, strlen($1) - 2);
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Path path2 = data->state.findFile(path);
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/* The file wasn't found in the search path. However, we can't
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throw an error here, because the expression might never be
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evaluated. So return an expression that lazily calls
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‘abort’. */
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$$ = path2 == ""
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? (Expr * ) new ExprApp(
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new ExprVar(data->symbols.create("throw")),
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new ExprString(data->symbols.create(
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(format("file `%1%' was not found in the Nix search path (add it using $NIX_PATH or -I)") % path).str())))
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: (Expr * ) new ExprPath(path2);
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}
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| URI { $$ = new ExprString(data->symbols.create($1)); }
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| '(' expr ')' { $$ = $2; }
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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; $$ = new ExprSelect($3, data->symbols.create("body")); }
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| REC '{' binds '}'
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{ $3->recursive = true; $$ = $3; }
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| '{' binds '}'
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{ $$ = $2; }
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| '[' expr_list ']' { $$ = $2; }
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;
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string_parts
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: string_parts STR { $$ = $1; $1->push_back($2); }
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| string_parts DOLLAR_CURLY expr '}' { backToString(scanner); $$ = $1; $1->push_back($3); }
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| { $$ = new vector<Expr *>; }
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;
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ind_string_parts
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: ind_string_parts IND_STR { $$ = $1; $1->push_back($2); }
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| ind_string_parts DOLLAR_CURLY expr '}' { backToIndString(scanner); $$ = $1; $1->push_back($3); }
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| { $$ = new vector<Expr *>; }
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;
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binds
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: binds attrpath '=' expr ';' { $$ = $1; addAttr($$, *$2, $4, makeCurPos(@2, data)); }
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| binds INHERIT attrs ';'
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{ $$ = $1;
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foreach (AttrPath::iterator, i, *$3) {
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if ($$->attrs.find(*i) != $$->attrs.end())
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dupAttr(*i, makeCurPos(@3, data), $$->attrs[*i].pos);
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Pos pos = makeCurPos(@3, data);
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$$->attrs[*i] = ExprAttrs::AttrDef(*i, pos);
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}
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}
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| binds INHERIT '(' expr ')' attrs ';'
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{ $$ = $1;
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/* !!! Should ensure sharing of the expression in $4. */
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foreach (vector<Symbol>::iterator, i, *$6) {
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if ($$->attrs.find(*i) != $$->attrs.end())
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dupAttr(*i, makeCurPos(@6, data), $$->attrs[*i].pos);
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$$->attrs[*i] = ExprAttrs::AttrDef(new ExprSelect($4, *i), makeCurPos(@6, data));
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}
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}
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| { $$ = new ExprAttrs; }
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;
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attrs
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: attrs attr { $$ = $1; $1->push_back(data->symbols.create($2)); /* !!! dangerous */ }
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| { $$ = new vector<Symbol>; }
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;
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attrpath
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: attrpath '.' attr { $$ = $1; $1->push_back(data->symbols.create($3)); }
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| attr { $$ = new vector<Symbol>; $$->push_back(data->symbols.create($1)); }
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;
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attr
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: ID { $$ = $1; }
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| OR_KW { $$ = "or"; }
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| '"' STR '"'
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{ $$ = strdup(((string) ((ExprString *) $2)->s).c_str()); delete $2; }
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;
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expr_list
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: expr_list expr_select { $$ = $1; $1->elems.push_back($2); /* !!! dangerous */ }
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| { $$ = new ExprList; }
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;
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formals
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: formal ',' formals
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{ $$ = $3; addFormal(CUR_POS, $$, *$1); }
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| formal
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{ $$ = new Formals; addFormal(CUR_POS, $$, *$1); $$->ellipsis = false; }
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|
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{ $$ = new Formals; $$->ellipsis = false; }
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| ELLIPSIS
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{ $$ = new Formals; $$->ellipsis = true; }
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;
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formal
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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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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <unistd.h>
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|
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#include <eval.hh>
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|
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namespace nix {
|
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|
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|
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Expr * EvalState::parse(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(*this);
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data.basePath = basePath;
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data.path = path;
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yylex_init(&scanner);
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yy_scan_string(text, scanner);
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int res = yyparse(scanner, &data);
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yylex_destroy(scanner);
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if (res) throw ParseError(data.error);
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try {
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data.result->bindVars(staticBaseEnv);
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} catch (Error & e) {
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throw ParseError(format("%1%, in `%2%'") % e.msg() % path);
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}
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|
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return data.result;
|
||
}
|
||
|
||
|
||
Expr * EvalState::parseExprFromFile(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, unless it's already in the parse
|
||
tree cache. */
|
||
Expr * e = parseTrees[path];
|
||
if (!e) {
|
||
e = parse(readFile(path).c_str(), path, dirOf(path));
|
||
parseTrees[path] = e;
|
||
}
|
||
|
||
return e;
|
||
}
|
||
|
||
|
||
Expr * EvalState::parseExprFromString(const string & s, const Path & basePath)
|
||
{
|
||
return parse(s.c_str(), "(string)", basePath);
|
||
}
|
||
|
||
|
||
void EvalState::addToSearchPath(const string & s)
|
||
{
|
||
size_t pos = s.find('=');
|
||
string prefix;
|
||
Path path;
|
||
if (pos == string::npos) {
|
||
path = s;
|
||
} else {
|
||
prefix = string(s, 0, pos);
|
||
path = string(s, pos + 1);
|
||
}
|
||
|
||
path = absPath(path);
|
||
if (pathExists(path)) {
|
||
debug(format("adding path `%1%' to the search path") % path);
|
||
searchPath.insert(searchPathInsertionPoint, std::pair<string, Path>(prefix, path));
|
||
}
|
||
}
|
||
|
||
|
||
Path EvalState::findFile(const string & path)
|
||
{
|
||
foreach (SearchPath::iterator, i, searchPath) {
|
||
Path res;
|
||
if (i->first.empty())
|
||
res = i->second + "/" + path;
|
||
else {
|
||
if (path.compare(0, i->first.size(), i->first) != 0 ||
|
||
(path.size() > i->first.size() && path[i->first.size()] != '/'))
|
||
continue;
|
||
res = i->second +
|
||
(path.size() == i->first.size() ? "" : "/" + string(path, i->first.size()));
|
||
}
|
||
if (pathExists(res)) return canonPath(res);
|
||
}
|
||
return "";
|
||
}
|
||
|
||
|
||
}
|