359 lines
13 KiB
Scheme
359 lines
13 KiB
Scheme
;; magrathea helps you build planets
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;;
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;; it is a tiny tool designed to ease workflows in monorepos that are
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;; modeled after the tvl depot.
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;;
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;; users familiar with workflows from other, larger monorepos may be
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;; used to having a build tool that can work in any tree location.
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;; magrathea enables this, but with nix-y monorepos.
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(import (chicken base)
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(chicken format)
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(chicken irregex)
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(chicken port)
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(chicken file)
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(chicken file posix)
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(chicken process)
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(chicken process-context)
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(chicken string)
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(matchable)
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(only (chicken io) read-string))
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(define usage #<<USAGE
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usage: mg <command> [<target>]
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target:
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a target specification with meaning inside of the repository. can
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be absolute (starting with //) or relative to the current directory
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(as long as said directory is inside of the repo). if no target is
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specified, the current directory's physical target is built.
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for example:
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//tools/magrathea - absolute physical target
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//foo/bar:baz - absolute virtual target
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magrathea - relative physical target
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:baz - relative virtual target
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commands:
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build - build a target
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shell - enter a shell with the target's build dependencies
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path - print source folder for the target
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run - build a target and execute its output
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file all feedback on b.tvl.fyi
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USAGE
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)
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;; parse target definitions. trailing slashes on physical targets are
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;; allowed for shell autocompletion.
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;;
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;; component ::= any string without "/" or ":"
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;;
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;; physical-target ::= <component>
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;; | <component> "/"
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;; | <component> "/" <physical-target>
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;;
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;; virtual-target ::= ":" <component>
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;;
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;; relative-target ::= <physical-target>
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;; | <virtual-target>
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;; | <physical-target> <virtual-target>
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;;
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;; root-anchor ::= "//"
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;;
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;; target ::= <relative-target> | <root-anchor> <relative-target>
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;; read a path component until it looks like something else is coming
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(define (read-component first port)
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(let ((keep-reading?
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(lambda () (not (or (eq? #\/ (peek-char port))
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(eq? #\: (peek-char port))
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(eof-object? (peek-char port)))))))
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(let reader ((acc (list first))
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(condition (keep-reading?)))
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(if condition (reader (cons (read-char port) acc) (keep-reading?))
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(list->string (reverse acc))))))
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;; read something that started with a slash. what will it be?
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(define (read-slash port)
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(if (eq? #\/ (peek-char port))
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(begin (read-char port)
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'root-anchor)
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'path-separator))
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;; read any target token and leave port sitting at the next one
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(define (read-token port)
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(match (read-char port)
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[#\/ (read-slash port)]
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[#\: 'virtual-separator]
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[other (read-component other port)]))
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;; read a target into a list of target tokens
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(define (read-target target-str)
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(call-with-input-string
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target-str
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(lambda (port)
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(let reader ((acc '()))
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(if (eof-object? (peek-char port))
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(reverse acc)
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(reader (cons (read-token port) acc)))))))
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(define-record target absolute components virtual)
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(define (empty-target) (make-target #f '() #f))
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(define-record-printer (target t out)
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(fprintf out (conc (if (target-absolute t) "//" "")
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(string-intersperse (target-components t) "/")
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(if (target-virtual t) ":" "")
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(or (target-virtual t) ""))))
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;; parse and validate a list of target tokens
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(define parse-tokens
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(lambda (tokens #!optional (mode 'root) (acc (empty-target)))
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(match (cons mode tokens)
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;; absolute target
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[('root . ('root-anchor . rest))
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(begin (target-absolute-set! acc #t)
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(parse-tokens rest 'root acc))]
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;; relative target minus potential garbage
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[('root . (not ('path-separator . _)))
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(parse-tokens tokens 'normal acc)]
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;; virtual target
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[('normal . ('virtual-separator . rest))
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(parse-tokens rest 'virtual acc)]
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[('virtual . ((? string? v)))
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(begin
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(target-virtual-set! acc v)
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acc)]
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;; chomp through all components and separators
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[('normal . ('path-separator . rest)) (parse-tokens rest 'normal acc)]
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[('normal . ((? string? component) . rest))
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(begin (target-components-set!
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acc (append (target-components acc) (list component)))
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(parse-tokens rest 'normal acc ))]
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;; nothing more to parse and not in a weird state, all done, yay!
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[('normal . ()) acc]
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;; oh no, we ran out of input too early :(
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[(_ . ()) `(error . ,(format "unexpected end of input while parsing ~s target" mode))]
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;; something else was invalid :(
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[_ `(error . ,(format "unexpected ~s while parsing ~s target" (car tokens) mode))])))
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(define (parse-target target)
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(parse-tokens (read-target target)))
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;; turn relative targets into absolute targets based on the current
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;; directory
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(define (normalise-target t)
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(when (not (target-absolute t))
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(target-components-set! t (append (relative-repo-path)
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(target-components t)))
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(target-absolute-set! t #t))
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t)
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;; nix doesn't care about the distinction between physical and virtual
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;; targets, normalise it away
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(define (normalised-components t)
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(if (target-virtual t)
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(append (target-components t) (list (target-virtual t)))
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(target-components t)))
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;; return the current repository root as a string
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(define mg--repository-root #f)
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(define (repository-root)
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(or mg--repository-root
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(begin
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(set! mg--repository-root
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(or (get-environment-variable "MG_ROOT")
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(string-chomp
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(call-with-input-pipe "git rev-parse --show-toplevel"
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(lambda (p) (read-string #f p))))))
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mg--repository-root)))
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;; determine the current path relative to the root of the repository
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;; and return it as a list of path components.
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(define (relative-repo-path)
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(string-split
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(substring (current-directory) (string-length (repository-root))) "/"))
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;; escape a string for interpolation in nix code
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(define (nix-escape str)
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(string-translate* str '(("\"" . "\\\"")
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("${" . "\\${"))))
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;; create a nix expression to build the attribute at the specified
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;; components
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;;
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;; an empty target will build the current folder instead.
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;;
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;; this uses builtins.getAttr explicitly to avoid problems with
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;; escaping.
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(define (nix-expr-for target)
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(let nest ((parts (normalised-components (normalise-target target)))
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(acc (conc "(import " (repository-root) " {})")))
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(match parts
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[() (conc "with builtins; " acc)]
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[_ (nest (cdr parts)
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(conc "(getAttr \""
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(nix-escape (car parts))
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"\" " acc ")"))])))
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;; exit and complain at the user if something went wrong
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(define (mg-error message)
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(format (current-error-port) "[mg] error: ~A~%" message)
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(exit 1))
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(define (guarantee-success value)
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(match value
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[('error . message) (mg-error message)]
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[_ value]))
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(define-record build-args target passthru unknown)
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(define (execute-build args)
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(let ((expr (nix-expr-for (build-args-target args))))
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(fprintf (current-error-port) "[mg] building target ~A~%" (build-args-target args))
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(process-execute "nix-build" (append (list "-E" expr "--show-trace")
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(or (build-args-passthru args) '())))))
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;; split the arguments used for builds into target/unknown args/nix
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;; args, where the latter occur after '--'
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(define (parse-build-args acc args)
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(match args
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;; no arguments remaining, return accumulator as is
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[() acc]
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;; next argument is '--' separator, split off passthru and
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;; return
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[("--" . passthru)
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(begin
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(build-args-passthru-set! acc passthru)
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acc)]
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[(arg . rest)
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;; set target if not already known (and if the first
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;; argument does not look like an accidental unknown
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;; parameter)
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(if (and (not (build-args-target acc))
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(not (substring=? "-" arg)))
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(begin
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(build-args-target-set! acc (guarantee-success (parse-target arg)))
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(parse-build-args acc rest))
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;; otherwise, collect unknown arguments
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(begin
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(build-args-unknown-set! acc (append (or (build-args-unknown acc) '())
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(list arg)))
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(parse-build-args acc rest)))]))
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;; parse the passed build args, applying sanity checks and defaulting
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;; the target if necessary, then execute the build
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(define (build args)
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(let ((parsed (parse-build-args (make-build-args #f #f #f) args)))
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;; fail if there are unknown arguments present
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(when (build-args-unknown parsed)
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(let ((unknown (string-intersperse (build-args-unknown parsed))))
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(mg-error (sprintf "unknown arguments: ~a
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if you meant to pass these arguments to nix, please separate them with
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'--' like so:
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mg build ~a -- ~a"
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unknown
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(or (build-args-target parsed) "")
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unknown))))
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;; default the target to the current folder's main target
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(unless (build-args-target parsed)
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(build-args-target-set! parsed (empty-target)))
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(execute-build parsed)))
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(define (execute-shell t)
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(let ((expr (nix-expr-for t))
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(user-shell (or (get-environment-variable "SHELL") "bash")))
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(fprintf (current-error-port) "[mg] entering shell for ~A~%" t)
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(process-execute "nix-shell"
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(list "-E" expr "--command" user-shell))))
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(define (shell args)
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(match args
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[() (execute-shell (empty-target))]
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[(arg) (execute-shell
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(guarantee-success (parse-target arg)))]
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[other (print "not yet implemented")]))
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(define (execute-run t #!optional cmd-args)
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(fprintf (current-error-port) "[mg] building target ~A~%" t)
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(let* ((expr (nix-expr-for t))
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(out (call-with-input-pipe
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(apply string-append
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;; TODO(sterni): temporary gc root
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(intersperse `("nix-build" "-E" ,(qs expr) "--no-out-link")
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" "))
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(lambda (p)
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(string-chomp (let ((s (read-string #f p)))
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(if (eq? s #!eof) "" s)))))))
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;; TODO(sterni): can we get the exit code of nix-build somehow?
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(when (= (string-length out) 0)
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(mg-error (string-append "Couldn't build target " (format "~A" t)))
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(exit 1))
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(fprintf (current-error-port) "[mg] running target ~A~%" t)
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(process-execute
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;; If the output is a file, we assume it's an executable à la writeExecline,
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;; otherwise we look in the bin subdirectory and pick the only executable.
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;; Handling multiple executables is not possible at the moment, the choice
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;; could be made via a command line flag in the future.
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(if (regular-file? out)
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out
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(let* ((dir-path (string-append out "/bin"))
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(dir-contents (if (directory-exists? dir-path)
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(directory dir-path #f)
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'())))
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(case (length dir-contents)
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((0) (mg-error "no executables in build output")
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(exit 1))
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((1) (string-append dir-path "/" (car dir-contents)))
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(else (mg-error "more than one executable in build output")
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(exit 1)))))
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cmd-args)))
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(define (run args)
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(match args
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[() (execute-run (empty-target))]
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;; TODO(sterni): flag for selecting binary name
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[other (execute-run (guarantee-success (parse-target (car args)))
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(cdr args))]))
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(define (path args)
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(match args
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[(arg)
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(print (apply string-append
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(intersperse
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(cons (repository-root)
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(target-components
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(normalise-target
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(guarantee-success (parse-target arg)))))
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"/")))]
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[() (mg-error "path command needs a target")]
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[other (mg-error (format "unknown arguments: ~a" other))]))
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(define (main args)
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(match args
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[() (print usage)]
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[("build" . _) (build (cdr args))]
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[("shell" . _) (shell (cdr args))]
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[("path" . _) (path (cdr args))]
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[("run" . _) (run (cdr args))]
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[other (begin (print "unknown command: mg " args)
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(print usage))]))
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(main (command-line-arguments))
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