Data commit

Task/Calendar/Rust/calendar.rust

@@ -0,0 +1,98 @@
+// Assume your binary name is 'calendar'.
+// Command line:
+// >>$ calendar 2019 150
+// First argument: year number.
+// Second argument (optional): text area width (in characters).
+
+extern crate chrono;
+
+use std::{env, cmp};
+use chrono::{NaiveDate, Datelike};
+
+const MONTH_WIDTH: usize = 22;
+
+fn print_header(months: &[&str]) {
+    const DAYS_OF_WEEK: &str = "SU MO TU WE TH FR SA  ";
+    println!();
+    for m in months {
+        print!("{:^20}  ", m);
+    }
+    println!("\n{}", DAYS_OF_WEEK.repeat(months.len()));
+}
+
+fn get_week_str(days: i32, week_num: i32, start_day_of_week: i32) -> Option<String> {
+    let start = week_num * 7 - start_day_of_week + 1;
+    let end = (week_num + 1) * 7 - start_day_of_week;
+    let mut ret = String::with_capacity(MONTH_WIDTH);
+    if start > days {
+        None
+    } else {
+        for i in start..(end + 1) {
+            if i <= 0 || i > days {
+                ret.push_str("  ");
+            } else {
+                if i < 10 {
+                    ret.push_str(" ");
+                }
+                ret.push_str(&i.to_string());
+            }
+            ret.push_str(" ");
+        }
+        ret.push_str(" ");
+        Some(ret)
+    }
+}
+
+fn main() {
+    const MONTH_NAMES: [&str; 12] = ["JANUARY", "FEBRUARY", "MARCH", "APRIL", "MAY", "JUNE", "JULY",
+                                     "AUGUST", "SEPTEMBER", "OCTOBER", "NOVEMBER", "DECEMBER"];
+    const DEFAULT_TEXT_WIDTH: usize = 100;
+
+    let args: Vec<String> = env::args().collect();
+    let year: i32 = args[1].parse().expect("The first argument must be a year");
+    let width: usize = if args.len() > 2 {
+        cmp::max(MONTH_WIDTH, args[2].parse().expect("The second argument should be text width"))
+    } else {
+        DEFAULT_TEXT_WIDTH
+    };
+    let months_in_row = width / MONTH_WIDTH;
+    let month_rows = if MONTH_NAMES.len() % months_in_row == 0 {
+        MONTH_NAMES.len() / months_in_row
+    } else {
+        MONTH_NAMES.len() / months_in_row + 1
+    };
+
+    let start_days_of_week: Vec<i32> =
+        (1..13).map(|x| NaiveDate::from_ymd(year, x, 1).weekday().num_days_from_sunday() as i32).collect();
+
+    let month_days: [i32; 12] = if NaiveDate::from_ymd_opt(year, 2, 29).is_some() {
+        [31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
+    } else {
+        [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
+    };
+
+    println!("{year:^w$}", w=width, year=year.to_string());
+    for i in 0..month_rows {
+        let start = i * months_in_row;
+        let end = cmp::min((i + 1) * months_in_row, MONTH_NAMES.len());
+        print_header(&MONTH_NAMES[start..end]);
+        let mut count = 0;
+        let mut row_num = 0;
+        while count < months_in_row {
+            let mut row_str = String::with_capacity(width);
+            for j in start..end {
+                match get_week_str(month_days[j], row_num, start_days_of_week[j]) {
+                    None => {
+                        count += 1;
+                        row_str.push_str(&" ".repeat(MONTH_WIDTH));
+                    },
+                    Some(week_str) => row_str.push_str(&week_str)
+                }
+            }
+            if count < months_in_row {
+                println!("{}", row_str);
+            }
+            row_num += 1;
+        }
+    }
+}