diff --git a/doc/manual/src/SUMMARY.md.in b/doc/manual/src/SUMMARY.md.in index 5df4e2d75..c8cb72fc0 100644 --- a/doc/manual/src/SUMMARY.md.in +++ b/doc/manual/src/SUMMARY.md.in @@ -34,7 +34,7 @@ - [Building and Testing](expressions/simple-building-testing.md) - [Generic Builder Syntax](expressions/generic-builder.md) - [Nix Expression Language](expressions/expression-language.md) - - [Values](expressions/language-values.md) + - [Data Types](expressions/language-values.md) - [Language Constructs](expressions/language-constructs.md) - [Operators](expressions/language-operators.md) - [Derivations](expressions/derivations.md) diff --git a/doc/manual/src/advanced-topics/distributed-builds.md b/doc/manual/src/advanced-topics/distributed-builds.md index b0d7fbf1a..fefd10100 100644 --- a/doc/manual/src/advanced-topics/distributed-builds.md +++ b/doc/manual/src/advanced-topics/distributed-builds.md @@ -12,14 +12,14 @@ machine is accessible via SSH and that it has Nix installed. You can test whether connecting to the remote Nix instance works, e.g. ```console -$ nix ping-store --store ssh://mac +$ nix store ping --store ssh://mac ``` will try to connect to the machine named `mac`. It is possible to specify an SSH identity file as part of the remote store URI, e.g. ```console -$ nix ping-store --store ssh://mac?ssh-key=/home/alice/my-key +$ nix store ping --store ssh://mac?ssh-key=/home/alice/my-key ``` Since builds should be non-interactive, the key should not have a diff --git a/doc/manual/src/expressions/language-values.md b/doc/manual/src/expressions/language-values.md index abbe1fd35..f09400d02 100644 --- a/doc/manual/src/expressions/language-values.md +++ b/doc/manual/src/expressions/language-values.md @@ -1,156 +1,164 @@ -# Values +# Data Types -## Simple Values +## Primitives -Nix has the following basic data types: +- String - - *Strings* can be written in three ways. - - The most common way is to enclose the string between double quotes, - e.g., `"foo bar"`. Strings can span multiple lines. The special - characters `"` and `\` and the character sequence `${` must be - escaped by prefixing them with a backslash (`\`). Newlines, carriage - returns and tabs can be written as `\n`, `\r` and `\t`, - respectively. - - You can include the result of an expression into a string by - enclosing it in `${...}`, a feature known as *antiquotation*. The - enclosed expression must evaluate to something that can be coerced - into a string (meaning that it must be a string, a path, or a - derivation). For instance, rather than writing - - ```nix - "--with-freetype2-library=" + freetype + "/lib" - ``` - - (where `freetype` is a derivation), you can instead write the more - natural - - ```nix - "--with-freetype2-library=${freetype}/lib" - ``` - - The latter is automatically translated to the former. A more - complicated example (from the Nix expression for - [Qt](http://www.trolltech.com/products/qt)): - - ```nix - configureFlags = " - -system-zlib -system-libpng -system-libjpeg - ${if openglSupport then "-dlopen-opengl - -L${mesa}/lib -I${mesa}/include - -L${libXmu}/lib -I${libXmu}/include" else ""} - ${if threadSupport then "-thread" else "-no-thread"} - "; - ``` - - Note that Nix expressions and strings can be arbitrarily nested; in - this case the outer string contains various antiquotations that - themselves contain strings (e.g., `"-thread"`), some of which in - turn contain expressions (e.g., `${mesa}`). - - The second way to write string literals is as an *indented string*, - which is enclosed between pairs of *double single-quotes*, like so: - - ```nix - '' - This is the first line. - This is the second line. - This is the third line. - '' - ``` - - This kind of string literal intelligently strips indentation from - the start of each line. To be precise, it strips from each line a - number of spaces equal to the minimal indentation of the string as a - whole (disregarding the indentation of empty lines). For instance, - the first and second line are indented two spaces, while the third - line is indented four spaces. Thus, two spaces are stripped from - each line, so the resulting string is - - ```nix - "This is the first line.\nThis is the second line.\n This is the third line.\n" - ``` - - Note that the whitespace and newline following the opening `''` is - ignored if there is no non-whitespace text on the initial line. - - Antiquotation (`${expr}`) is supported in indented strings. - - Since `${` and `''` have special meaning in indented strings, you - need a way to quote them. `$` can be escaped by prefixing it with - `''` (that is, two single quotes), i.e., `''$`. `''` can be escaped - by prefixing it with `'`, i.e., `'''`. `$` removes any special - meaning from the following `$`. Linefeed, carriage-return and tab - characters can be written as `''\n`, `''\r`, `''\t`, and `''\` - escapes any other character. - - Indented strings are primarily useful in that they allow multi-line - string literals to follow the indentation of the enclosing Nix - expression, and that less escaping is typically necessary for - strings representing languages such as shell scripts and - configuration files because `''` is much less common than `"`. - Example: - - ```nix - stdenv.mkDerivation { - ... - postInstall = - '' - mkdir $out/bin $out/etc - cp foo $out/bin - echo "Hello World" > $out/etc/foo.conf - ${if enableBar then "cp bar $out/bin" else ""} - ''; - ... - } - ``` - - Finally, as a convenience, *URIs* as defined in appendix B of - [RFC 2396](http://www.ietf.org/rfc/rfc2396.txt) can be written *as - is*, without quotes. For instance, the string - `"http://example.org/foo.tar.bz2"` can also be written as - `http://example.org/foo.tar.bz2`. + *Strings* can be written in three ways. - - Numbers, which can be *integers* (like `123`) or *floating point* - (like `123.43` or `.27e13`). - - Numbers are type-compatible: pure integer operations will always - return integers, whereas any operation involving at least one - floating point number will have a floating point number as a result. + The most common way is to enclose the string between double quotes, + e.g., `"foo bar"`. Strings can span multiple lines. The special + characters `"` and `\` and the character sequence `${` must be + escaped by prefixing them with a backslash (`\`). Newlines, carriage + returns and tabs can be written as `\n`, `\r` and `\t`, + respectively. - - *Paths*, e.g., `/bin/sh` or `./builder.sh`. A path must contain at - least one slash to be recognised as such. For instance, `builder.sh` - is not a path: it's parsed as an expression that selects the - attribute `sh` from the variable `builder`. If the file name is - relative, i.e., if it does not begin with a slash, it is made - absolute at parse time relative to the directory of the Nix - expression that contained it. For instance, if a Nix expression in - `/foo/bar/bla.nix` refers to `../xyzzy/fnord.nix`, the absolute path - is `/foo/xyzzy/fnord.nix`. - - If the first component of a path is a `~`, it is interpreted as if - the rest of the path were relative to the user's home directory. - e.g. `~/foo` would be equivalent to `/home/edolstra/foo` for a user - whose home directory is `/home/edolstra`. - - Paths can also be specified between angle brackets, e.g. - ``. This means that the directories listed in the - environment variable `NIX_PATH` will be searched for the given file - or directory name. + You can include the result of an expression into a string by + enclosing it in `${...}`, a feature known as *antiquotation*. The + enclosed expression must evaluate to something that can be coerced + into a string (meaning that it must be a string, a path, or a + derivation). For instance, rather than writing - Antiquotation is supported in any paths except those in angle brackets. - `./${foo}-${bar}.nix` is a more convenient way of writing - `./. + "/" + foo + "-" + bar + ".nix"` or `./. + "/${foo}-${bar}.nix"`. At - least one slash must appear *before* any antiquotations for this to be - recognized as a path. `a.${foo}/b.${bar}` is a syntactically valid division - operation. `./a.${foo}/b.${bar}` is a path. + ```nix + "--with-freetype2-library=" + freetype + "/lib" + ``` - - *Booleans* with values `true` and `false`. + (where `freetype` is a derivation), you can instead write the more + natural - - The null value, denoted as `null`. + ```nix + "--with-freetype2-library=${freetype}/lib" + ``` -## Lists + The latter is automatically translated to the former. A more + complicated example (from the Nix expression for + [Qt](http://www.trolltech.com/products/qt)): + + ```nix + configureFlags = " + -system-zlib -system-libpng -system-libjpeg + ${if openglSupport then "-dlopen-opengl + -L${mesa}/lib -I${mesa}/include + -L${libXmu}/lib -I${libXmu}/include" else ""} + ${if threadSupport then "-thread" else "-no-thread"} + "; + ``` + + Note that Nix expressions and strings can be arbitrarily nested; in + this case the outer string contains various antiquotations that + themselves contain strings (e.g., `"-thread"`), some of which in + turn contain expressions (e.g., `${mesa}`). + + The second way to write string literals is as an *indented string*, + which is enclosed between pairs of *double single-quotes*, like so: + + ```nix + '' + This is the first line. + This is the second line. + This is the third line. + '' + ``` + + This kind of string literal intelligently strips indentation from + the start of each line. To be precise, it strips from each line a + number of spaces equal to the minimal indentation of the string as a + whole (disregarding the indentation of empty lines). For instance, + the first and second line are indented two spaces, while the third + line is indented four spaces. Thus, two spaces are stripped from + each line, so the resulting string is + + ```nix + "This is the first line.\nThis is the second line.\n This is the third line.\n" + ``` + + Note that the whitespace and newline following the opening `''` is + ignored if there is no non-whitespace text on the initial line. + + Antiquotation (`${expr}`) is supported in indented strings. + + Since `${` and `''` have special meaning in indented strings, you + need a way to quote them. `$` can be escaped by prefixing it with + `''` (that is, two single quotes), i.e., `''$`. `''` can be escaped + by prefixing it with `'`, i.e., `'''`. `$` removes any special + meaning from the following `$`. Linefeed, carriage-return and tab + characters can be written as `''\n`, `''\r`, `''\t`, and `''\` + escapes any other character. + + Indented strings are primarily useful in that they allow multi-line + string literals to follow the indentation of the enclosing Nix + expression, and that less escaping is typically necessary for + strings representing languages such as shell scripts and + configuration files because `''` is much less common than `"`. + Example: + + ```nix + stdenv.mkDerivation { + ... + postInstall = + '' + mkdir $out/bin $out/etc + cp foo $out/bin + echo "Hello World" > $out/etc/foo.conf + ${if enableBar then "cp bar $out/bin" else ""} + ''; + ... + } + ``` + + Finally, as a convenience, *URIs* as defined in appendix B of + [RFC 2396](http://www.ietf.org/rfc/rfc2396.txt) can be written *as + is*, without quotes. For instance, the string + `"http://example.org/foo.tar.bz2"` can also be written as + `http://example.org/foo.tar.bz2`. + +- Number + + Numbers, which can be *integers* (like `123`) or *floating point* + (like `123.43` or `.27e13`). + + Numbers are type-compatible: pure integer operations will always + return integers, whereas any operation involving at least one + floating point number will have a floating point number as a result. + +- Path + + *Paths*, e.g., `/bin/sh` or `./builder.sh`. A path must contain at + least one slash to be recognised as such. For instance, `builder.sh` + is not a path: it's parsed as an expression that selects the + attribute `sh` from the variable `builder`. If the file name is + relative, i.e., if it does not begin with a slash, it is made + absolute at parse time relative to the directory of the Nix + expression that contained it. For instance, if a Nix expression in + `/foo/bar/bla.nix` refers to `../xyzzy/fnord.nix`, the absolute path + is `/foo/xyzzy/fnord.nix`. + + If the first component of a path is a `~`, it is interpreted as if + the rest of the path were relative to the user's home directory. + e.g. `~/foo` would be equivalent to `/home/edolstra/foo` for a user + whose home directory is `/home/edolstra`. + + Paths can also be specified between angle brackets, e.g. + ``. This means that the directories listed in the + environment variable `NIX_PATH` will be searched for the given file + or directory name. + + Antiquotation is supported in any paths except those in angle brackets. + `./${foo}-${bar}.nix` is a more convenient way of writing + `./. + "/" + foo + "-" + bar + ".nix"` or `./. + "/${foo}-${bar}.nix"`. At + least one slash must appear *before* any antiquotations for this to be + recognized as a path. `a.${foo}/b.${bar}` is a syntactically valid division + operation. `./a.${foo}/b.${bar}` is a path. + +- Boolean + + *Booleans* with values `true` and `false`. + +- Null + + The null value, denoted as `null`. + +## List Lists are formed by enclosing a whitespace-separated list of values between square brackets. For example, @@ -172,9 +180,9 @@ function and the fifth being a set. Note that lists are only lazy in values, and they are strict in length. -## Attribute Sets +## Attribute Set -Attribute sets are collections of name-value-pairs (called *attributes*) enclosed in curly brackets (`{ }`). +An attribute set is a collection of name-value-pairs (called *attributes*) enclosed in curly brackets (`{ }`). Names and values are separated by an equal sign (`=`). Each value is an arbitrary expression terminated by a semicolon (`;`). diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc index f485e2fed..e3716f217 100644 --- a/src/libexpr/eval.cc +++ b/src/libexpr/eval.cc @@ -2501,18 +2501,18 @@ void EvalState::printStats() } { auto list = topObj.list("functions"); - for (auto & i : functionCalls) { + for (auto & [fun, count] : functionCalls) { auto obj = list.object(); - if (i.first->name) - obj.attr("name", (const std::string &) i.first->name); + if (fun->name) + obj.attr("name", (std::string_view) symbols[fun->name]); else obj.attr("name", nullptr); - if (auto pos = positions[i.first->pos]) { - obj.attr("file", (const std::string &) pos.file); + if (auto pos = positions[fun->pos]) { + obj.attr("file", (std::string_view) pos.file); obj.attr("line", pos.line); obj.attr("column", pos.column); } - obj.attr("count", i.second); + obj.attr("count", count); } } { diff --git a/src/libutil/json.cc b/src/libutil/json.cc index b0a5d7e75..abe0e6e74 100644 --- a/src/libutil/json.cc +++ b/src/libutil/json.cc @@ -6,7 +6,8 @@ namespace nix { -void toJSON(std::ostream & str, const char * start, const char * end) +template<> +void toJSON(std::ostream & str, const std::string_view & s) { constexpr size_t BUF_SIZE = 4096; char buf[BUF_SIZE + 7]; // BUF_SIZE + largest single sequence of puts @@ -21,7 +22,7 @@ void toJSON(std::ostream & str, const char * start, const char * end) }; put('"'); - for (auto i = start; i != end; i++) { + for (auto i = s.begin(); i != s.end(); i++) { if (bufPos >= BUF_SIZE) flush(); if (*i == '\"' || *i == '\\') { put('\\'); put(*i); } else if (*i == '\n') { put('\\'); put('n'); } @@ -44,7 +45,7 @@ void toJSON(std::ostream & str, const char * start, const char * end) void toJSON(std::ostream & str, const char * s) { - if (!s) str << "null"; else toJSON(str, s, s + strlen(s)); + if (!s) str << "null"; else toJSON(str, std::string_view(s)); } template<> void toJSON(std::ostream & str, const int & n) { str << n; } @@ -55,11 +56,7 @@ template<> void toJSON(std::ostream & str, const long long & n) { str template<> void toJSON(std::ostream & str, const unsigned long long & n) { str << n; } template<> void toJSON(std::ostream & str, const float & n) { str << n; } template<> void toJSON(std::ostream & str, const double & n) { str << n; } - -template<> void toJSON(std::ostream & str, const std::string & s) -{ - toJSON(str, s.c_str(), s.c_str() + s.size()); -} +template<> void toJSON(std::ostream & str, const std::string & s) { toJSON(str, (std::string_view) s); } template<> void toJSON(std::ostream & str, const bool & b) { @@ -154,7 +151,7 @@ JSONObject::~JSONObject() } } -void JSONObject::attr(const std::string & s) +void JSONObject::attr(std::string_view s) { comma(); toJSON(state->str, s); @@ -162,19 +159,19 @@ void JSONObject::attr(const std::string & s) if (state->indent) state->str << ' '; } -JSONList JSONObject::list(const std::string & name) +JSONList JSONObject::list(std::string_view name) { attr(name); return JSONList(state); } -JSONObject JSONObject::object(const std::string & name) +JSONObject JSONObject::object(std::string_view name) { attr(name); return JSONObject(state); } -JSONPlaceholder JSONObject::placeholder(const std::string & name) +JSONPlaceholder JSONObject::placeholder(std::string_view name) { attr(name); return JSONPlaceholder(state); diff --git a/src/libutil/json.hh b/src/libutil/json.hh index 83213ca66..3790b1a2e 100644 --- a/src/libutil/json.hh +++ b/src/libutil/json.hh @@ -6,7 +6,6 @@ namespace nix { -void toJSON(std::ostream & str, const char * start, const char * end); void toJSON(std::ostream & str, const char * s); template @@ -107,7 +106,7 @@ private: open(); } - void attr(const std::string & s); + void attr(std::string_view s); public: @@ -128,18 +127,18 @@ public: ~JSONObject(); template - JSONObject & attr(const std::string & name, const T & v) + JSONObject & attr(std::string_view name, const T & v) { attr(name); toJSON(state->str, v); return *this; } - JSONList list(const std::string & name); + JSONList list(std::string_view name); - JSONObject object(const std::string & name); + JSONObject object(std::string_view name); - JSONPlaceholder placeholder(const std::string & name); + JSONPlaceholder placeholder(std::string_view name); }; class JSONPlaceholder : JSONWriter diff --git a/src/libutil/tests/json.cc b/src/libutil/tests/json.cc index dea73f53a..156286999 100644 --- a/src/libutil/tests/json.cc +++ b/src/libutil/tests/json.cc @@ -102,8 +102,8 @@ namespace nix { TEST(toJSON, substringEscape) { std::stringstream out; - const char *s = "foo\t"; - toJSON(out, s+3, s + strlen(s)); + std::string_view s = "foo\t"; + toJSON(out, s.substr(3)); ASSERT_EQ(out.str(), "\"\\t\""); }