656c168a52
A dice table is a direct translation of a gaming table from a book, where the table has a stated dice expression, and each entry has a numeric range. Most tables can now be taken as is from published sources. Also, if a message from a randomly rolled table contains a dice expression, like Found 2d8 scrolls, the expression is automatically substituted. Finally if a message contains something like: You found a [wolf/fox/badger]. The displayed message will only include on of those entries.
86 lines
3.6 KiB
EmacsLisp
86 lines
3.6 KiB
EmacsLisp
;;; rpgdm-tables-dice.el --- Rolling dice for choosing items from Tables -*- lexical-binding: t; -*-
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;;
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;; Copyright (C) 2021 Howard X. Abrams
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;;
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;; Author: Howard X. Abrams <http://gitlab.com/howardabrams>
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;; Maintainer: Howard X. Abrams <howard.abrams@gmail.com>
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;; Created: February 5, 2021
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;;
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;; This file is not part of GNU Emacs.
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;;
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;;
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;;; Commentary:
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;;
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;; This file contains the source code, but the concept behind what I'm
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;; calling random dice tables is a bit complex, so I recommend looking
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;; at the original file in `docs/rpgdm-tables-dice.org'.
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;;; Code:
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(defstruct dice-table dice rows)
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(defun rpgdm-tables--choose-dice-table (table)
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"Choose a string from a random dice table."
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(let* ((roll (rpgdm-roll-sum (dice-table-dice table)))
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(rows (dice-table-rows table))
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(results (rpgdm-tables-dice--choose roll rows)))
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(if (stringp results)
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results
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(seq-random-elt results))))
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(defun rpgdm-tables-dice--choose (roll rows)
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"Given a numeric ROLL, return row that matches.
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This assumes ROWS is a sorted list where the first element (the
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`car') is a numeric level that if ROLL is less than or equal, we
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return the `rest' of the row. Otherwise, we recursively call this
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function with the `rest' of the rows."
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(let* ((row (first rows))
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(level (car row))
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(answer (rest row)))
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(if (<= roll level)
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answer
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(rpgdm-tables-dice--choose roll (rest rows)))))
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(setq rpgdm-tables-dice-table-regexp (rx "Roll"
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(one-or-more space)
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(optional (or "on" "for"))
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(zero-or-more space)
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"Table:"
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(zero-or-more space)
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(group
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(regexp rpgdm-roll-regexp))))
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(defun rpgdm-tables-dice-table? ()
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"Return non-nil if current buffer contains a dice-table"
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(goto-char (point-min))
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(re-search-forward rpgdm-tables-dice-table-regexp nil t))
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(defun rpgdm-tables--parse-as-dice-table ()
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"Return `dice-table' of lines matching `rpgdm-tables-dice-table-rows'."
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(let ((dice (match-string-no-properties 1)) ; Grab expression before moving on
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(rows ()) ; Modify this with add-to-list
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(row-splitter (rx (* space) "|" (* space)))) ; Split rest of table row
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(while (re-search-forward rgpdm-tables-dice-table-rows nil t)
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(let* ((levelstr (match-string-no-properties 1))
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(level (string-to-number levelstr))
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(row (match-string-no-properties 2))
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(choices (split-string row row-splitter t)))
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(add-to-list 'rows (cons level choices))))
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(make-dice-table :dice dice
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:rows (sort rows (lambda (a b) (< (first a) (first b)))))))
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(setq rgpdm-tables-dice-table-rows (rx bol
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(zero-or-more space) "|" (zero-or-more space)
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(optional (one-or-more digit)
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(one-or-more "-"))
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(group
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(one-or-more digit))
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(zero-or-more space) "|" (zero-or-more space)
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(group (+? any))
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(zero-or-more space) "|" (zero-or-more space)
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eol))
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(provide 'rpgdm-tables-dice)
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;;; rpgdm-tables-dice.el ends here
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