diff options
Diffstat (limited to 'lib/strings.nix')
-rw-r--r-- | lib/strings.nix | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/lib/strings.nix b/lib/strings.nix index 11066890ec3d3..bad8f53fa565b 100644 --- a/lib/strings.nix +++ b/lib/strings.nix @@ -17,6 +17,7 @@ rec { head isInt isList + isAttrs isString match parseDrvName @@ -324,6 +325,65 @@ rec { */ escapeShellArgs = concatMapStringsSep " " escapeShellArg; + /* Test whether the given name is a valid POSIX shell variable name. + + Type: string -> bool + + Example: + isValidPosixName "foo_bar000" + => true + isValidPosixName "0-bad.jpg" + => false + */ + isValidPosixName = name: match "[a-zA-Z_][a-zA-Z0-9_]*" name != null; + + /* Translate a Nix value into a shell variable declaration, with proper escaping. + + Supported value types are strings (mapped to regular variables), lists of strings + (mapped to Bash-style arrays) and attribute sets of strings (mapped to Bash-style + associative arrays). Note that "strings" include string-coercible values like paths. + + Strings are translated into POSIX sh-compatible code; lists and attribute sets + assume a shell that understands Bash syntax (e.g. Bash or ZSH). + + Type: string -> (string | listOf string | attrsOf string) -> string + + Example: + '' + ${toShellVar foo "some string"} + [[ "$foo" == "some string" ]] + '' + */ + toShellVar = name: value: + lib.throwIfNot (isValidPosixName name) "toShellVar: ${name} is not a valid shell variable name" ( + if isAttrs value then + "declare -A ${name}=(${ + concatStringsSep " " (lib.mapAttrsToList (n: v: + "[${escapeShellArg n}]=${escapeShellArg v}" + ) value) + })" + else if isList value then + "declare -a ${name}=(${escapeShellArgs value})" + else + "${name}=${escapeShellArg value}" + ); + + /* Translate an attribute set into corresponding shell variable declarations + using `toShellVar`. + + Type: attrsOf (string | listOf string | attrsOf string) -> string + + Example: + let + foo = "value"; + bar = foo; + in '' + ${toShellVars { inherit foo bar; }} + [[ "$foo" == "$bar" ]] + '' + */ + toShellVars = vars: concatStringsSep "\n" (lib.mapAttrsToList toShellVar vars); + /* Turn a string into a Nix expression representing that string Type: string -> string |