Awk grains

awk/README.md

@@ -25,3 +25,4 @@
 - [raindrops](./raindrops/README.md)
 - [leap](./leap/README.md)
 - [armstrong-numbers](./armstrong-numbers/README.md)
+- [grains](./grains/README.md)

awk/grains/.exercism/config.json

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+{
+  "authors": [
+    "glennj"
+  ],
+  "files": {
+    "solution": [
+      "grains.awk"
+    ],
+    "test": [
+      "test-grains.bats"
+    ],
+    "example": [
+      ".meta/example.awk"
+    ]
+  },
+  "blurb": "Calculate the number of grains of wheat on a chessboard given that the number on each square doubles.",
+  "source": "The CodeRanch Cattle Drive, Assignment 6",
+  "source_url": "https://coderanch.com/wiki/718824/Grains"
+}

awk/grains/.exercism/metadata.json

@@ -0,0 +1 @@
+{"track":"awk","exercise":"grains","id":"1a3045dfcd1642978c12499b7080a7f3","url":"https://exercism.org/tracks/awk/exercises/grains","handle":"vpayno","is_requester":true,"auto_approve":false}

awk/grains/.lint_default_vars

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+ -M

awk/grains/HELP.md

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+# Help
+
+## Running the tests
+
+Each exercise contains a test file.
+Run the tests using the `bats` program.
+```bash
+bats test-hello-world.bats
+```
+
+`bats` will need to be installed.
+See the [Testing on the Bash track][bash] page for instructions to install `bats` for your system.
+
+### bats is implemented in bash
+
+The bats file is a bash script, with some special functions recognized by the `bats` command.
+You'll see some tests that look like
+```sh
+gawk -f some-exercise.awk <<< "some,input,here"
+```
+That `<<<` syntax is a bash [Here String][here-string].
+It sends the string on the right-hand side into the standard input of the program on the left-hand side.
+It is ([approximately][so]) the same as
+```sh
+echo "some,input,here" | gawk -f some-exercise.awk
+```
+
+## Help for assert functions
+
+The tests use functions from the [bats-assert][bats-assert] library.
+Help for the various `assert*` functions can be found there.
+
+## Skipped tests
+
+Solving an exercise means making all its tests pass.
+By default, only one test (the first one) is executed when you run the tests.
+This is intentional, as it allows you to focus on just making that one test pass.
+Once it passes, you can enable the next test by commenting out or removing the
+
+    [[ $BATS_RUN_SKIPPED == true ]] || skip
+
+annotations prepending other tests.
+
+## Overriding skips
+
+To run all tests, including the ones with `skip` annotations, you can run:
+```bash
+BATS_RUN_SKIPPED=true bats test-some-exercise.bats
+```
+
+It can be convenient to use a wrapper function to save on typing: in `bash` you can do:
+```bash
+bats() {
+    BATS_RUN_SKIPPED=true command bats *.bats
+}
+```
+Then run tests with just:
+```bash
+bats
+```
+
+[bash]: https://exercism.org/docs/tracks/bash/tests
+[bats-assert]: https://github.com/bats-core/bats-assert
+[here-string]: https://www.gnu.org/software/bash/manual/bash.html#Here-Strings
+[so]: https://unix.stackexchange.com/a/80372/4667
+
+## Submitting your solution
+
+You can submit your solution using the `exercism submit grains.awk` command.
+This command will upload your solution to the Exercism website and print the solution page's URL.
+
+It's possible to submit an incomplete solution which allows you to:
+
+- See how others have completed the exercise
+- Request help from a mentor
+
+## Need to get help?
+
+If you'd like help solving the exercise, check the following pages:
+
+- The [AWK track's documentation](https://exercism.org/docs/tracks/awk)
+- [Exercism's programming category on the forum](https://forum.exercism.org/c/programming/5)
+- The [Frequently Asked Questions](https://exercism.org/docs/using/faqs)
+
+Should those resources not suffice, you could submit your (incomplete) solution to request mentoring.
+
+Places to look for help for AWK questions:
+
+* [Stack Overflow `awk` tag][so].
+* check the Resources section of the [Stack Overflow `awk` tag into page][so-info].
+* raise an issue at the [exercism/awk][github] Github repository.
+* IRC: `irc://irc.liberachat.net/#awk`, `irc://irc.liberachat.net/#exercism`
+    * see [Libera.chat][libera] if you're unfamiliar with IRC.
+
+
+[so]: https://stackoverflow.com/tags/awk
+[so-info]: https://stackoverflow.com/tags/awk/info
+[github]: https://github.com/exercism/awk
+[libera]: https://libera.chat

awk/grains/README.md

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+# Grains
+
+Welcome to Grains on Exercism's AWK Track.
+If you need help running the tests or submitting your code, check out `HELP.md`.
+
+## Instructions
+
+Calculate the number of grains of wheat on a chessboard given that the number on each square doubles.
+
+There once was a wise servant who saved the life of a prince.
+The king promised to pay whatever the servant could dream up.
+Knowing that the king loved chess, the servant told the king he would like to have grains of wheat.
+One grain on the first square of a chess board, with the number of grains doubling on each successive square.
+
+There are 64 squares on a chessboard (where square 1 has one grain, square 2 has two grains, and so on).
+
+Write code that shows:
+
+- how many grains were on a given square, and
+- the total number of grains on the chessboard
+
+## GNU awk and Arbitrary Precision Arithmetic
+
+By default, numbers in `awk` are represented as double-precision floating
+point numbers.  This provides 53 bits of precision (see [Table
+16.3][table-16.3] in the manual).  Unfortunately, this is insufficient to
+complete this exercise (spoiler alert, one test requires 63 bits of
+precision).
+
+"Insufficient precision" looks like this:
+```sh
+$ gawk 'BEGIN {
+  n = 2 ^ 54
+  if (n == n + 1)
+    print "not enough precision"
+  else
+    print "OK"
+}'
+```
+```none
+not enough precision
+```
+
+GNU `awk` has the capability to use arbitrary-precision numbers, if the
+relevant libraries have been compiled into the `awk` executable. Check
+your awk version, and look for "GNU MPFR":
+```sh
+$ gawk --version
+GNU Awk 5.0.1, API: 2.0 (GNU MPFR 4.0.2, GNU MP 6.2.0)
+...
+```
+
+If it's present, enable the capability using the `-M` option:
+```sh
+$ gawk -M 'BEGIN {
+  n = 2 ^ 54
+  if (n == n + 1)
+    print "not enough precision"
+  else
+    print "OK"
+}'
+```
+```none
+OK
+```
+
+What if my `awk` doesn't have `-M`?  You'll have to call out to an external
+program that can do arbitrary precision arithmetic, like `bc`. See the
+section [Using getline into a Variable from a Pipe][getline-pipe] for an
+example how to do this.
+
+
+Further reading: [Arbitrary Precision Arithmetic][arbitrary]
+
+
+[table-16.3]: https://www.gnu.org/software/gawk/manual/html_node/Math-Definitions.html#table_002dieee_002dformats
+[arbitrary]: https://www.gnu.org/software/gawk/manual/html_node/Arbitrary-Precision-Arithmetic.html
+[getline-pipe]: https://www.gnu.org/software/gawk/manual/html_node/Getline_002fVariable_002fPipe.html
+
+## Source
+
+### Created by
+
+- @glennj
+
+### Based on
+
+The CodeRanch Cattle Drive, Assignment 6 - https://coderanch.com/wiki/718824/Grains
+
+### My Solution
+
+- [my solution](./grains.awk)
+- [awkunit tests](./grains_test.awk)
+- [test cases](./test-cases.awk)
+- [run-tests](./run-tests-awk.txt)

awk/grains/awkunit.awk

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+../.lib/awkunit.awk