New day counter (#55)

* Bump deps and use uv

* Better day counters

* vibe coding

* vibe coding

Author: lsbardel

.github/copilot-instructions.md

@@ -21,3 +21,4 @@ applyTo: '/**'
 * The documentation for ccy is available at `https://ccy.quantmid.com`
 * Documentation is built using [mkdocs](https://www.mkdocs.org/) and stored in the `docs/` directory. The documentation source files are written in markdown format.
 * Do not use em dashes (—) in documentation files or docstrings. Use colons, parentheses, or restructure the sentence instead.
+* To link to a class or function in documentation, use the mkdocstrings cross-reference notation: `[ClassName][module.path.ClassName]` (e.g. `[TradingCentre][ccy.tradingcentres.TradingCentre]`)

Makefile

@@ -38,7 +38,7 @@ docs:		## Build mkdocs site
 
 .PHONY: docs-serve
 docs-serve:	## Serve docs locally with live reload
-	uv run mkdocs serve
+	uv run mkdocs serve --livereload --watch ccy --watch docs
 
 .PHONY: publish-docs
 publish-docs:	## Publish docs to github pages

ccy/__init__.py

@@ -20,7 +20,7 @@
     currencydb,
     dump_currency_table,
 )
-from .core.daycounter import alldc, getdc
+from .core.daycounter import DayCounter
 from .dates.converters import (
     date2juldate,
     date2timestamp,
@@ -42,8 +42,7 @@
     "currency_pair",
     "dump_currency_table",
     #
-    "getdc",
-    "alldc",
+    "DayCounter",
     #
     "country",
     "countryccy",

ccy/core/daycounter.py

@@ -1,81 +1,58 @@
-"""Day Counter for Counting time between 2 dates.
-Implemented::
-
-    * Actual 360
-    * Actual 365
-    * 30 / 360
-    * Actual Actual
-"""
-
 from __future__ import annotations
 
-from copy import copy
 from datetime import date
-from typing import Any
-from ..dates.utils import date_diff
-
-__all__ = ["getdc", "DayCounter", "alldc"]
-
-
-def getdc(name: str) -> DayCounter:
-    return _day_counters[name]()
-
-
-def alldc() -> dict[str, DayCounterMeta]:
-    global _day_counters
-    return copy(_day_counters)
-
-
-class DayCounterMeta(type):
-    def __new__(cls, name: str, bases: Any, attrs: Any) -> DayCounterMeta:
-        new_class = super(DayCounterMeta, cls).__new__(cls, name, bases, attrs)
-        if name := getattr(new_class, "name", ""):
-            _day_counters[name] = new_class
-        return new_class
-
-
-_day_counters: dict[str, DayCounterMeta] = {}
-
-
-class DayCounter(metaclass=DayCounterMeta):
-    name: str = ""
-
-    def count(self, start: date, end: date) -> float:
-        """Count the number of days between 2 dates"""
-        return date_diff(end, start).total_seconds() / 86400
-
-    def dcf(self, start: date, end: date) -> float:
-        return self.count(start, end) / 360.0
-
-
-class Act360(DayCounter):
-    name = "ACT/360"
-
-
-class Act365(DayCounter):
-    name = "ACT/365"
-
-    def dcf(self, start: date, end: date) -> float:
-        return self.count(start, end) / 365.0
+from enum import StrEnum
 
+from ..dates.utils import date_diff
 
-class Thirty360(DayCounter):
-    name = "30/360"
+__all__ = ["DayCounter"]
 
-    def dcf(self, start: date, end: date) -> float:
-        d1 = min(start.day, 30)
-        d2 = min(end.day, 30)
-        return 360 * (end.year - start.year) + 30 * (end.month - start.month) + d2 - d1
 
+class DayCounter(StrEnum):
+    """Day count convention types"""
 
-class ActAct(DayCounter):
-    name = "ACT/ACT"
+    ACT360 = "ACT/360"
+    ACT365 = "ACT/365"
+    THIRTY360 = "30/360"
+    THIRTYE360 = "30E/360"
+    ACTACT = "ACT/ACT"
 
     def dcf(self, start: date, end: date) -> float:
-        return self.act_act_years(end) - self.act_act_years(start)
-
-    def act_act_years(self, dt: date) -> float:
-        y = dt.year
-        days_in_year = 365 if y % 4 else 366
-        dd = date_diff(dt, date(y, 1, 1)).total_seconds() / 86400
-        return y + dd / days_in_year
+        """Day count fraction between 2 dates"""
+        match self:
+            case DayCounter.ACT360:
+                return count_days(start, end) / 360.0
+            case DayCounter.ACT365:
+                return count_days(start, end) / 365.0
+            case DayCounter.THIRTY360:
+                return _thirty_360(start, end)
+            case DayCounter.THIRTYE360:
+                return _thirty_e360(start, end)
+            case DayCounter.ACTACT:
+                return _act_act_years(end) - _act_act_years(start)
+            case _:
+                raise ValueError(f"Unknown day counter: {self}")
+
+
+def count_days(start: date, end: date) -> float:
+    """Count the number of days between 2 dates"""
+    return date_diff(end, start).total_seconds() / 86400
+
+
+def _thirty_e360(start: date, end: date) -> float:
+    d1 = min(start.day, 30)
+    d2 = min(end.day, 30)
+    return 360 * (end.year - start.year) + 30 * (end.month - start.month) + d2 - d1
+
+
+def _thirty_360(start: date, end: date) -> float:
+    d1 = min(start.day, 30)
+    d2 = min(end.day, 30) if d1 == 30 else end.day
+    return 360 * (end.year - start.year) + 30 * (end.month - start.month) + d2 - d1
+
+
+def _act_act_years(dt: date) -> float:
+    y = dt.year
+    days_in_year = 365 if y % 4 else 366
+    dd = date_diff(dt, date(y, 1, 1)).total_seconds() / 86400
+    return y + dd / days_in_year

ccy/tradingcentres/__init__.py

@@ -1,26 +1,47 @@
 from __future__ import annotations
 
-from dataclasses import dataclass, field
 from datetime import date, timedelta
+from typing_extensions import Annotated, Doc
+
 import holidays
 import holidays.countries
 import holidays.financial
+from pydantic import BaseModel, Field
 
 isoweekend = frozenset((6, 7))
 oneday = timedelta(days=1)
 
 trading_centres: dict[str, TradingCentre] = {}
 
 
-def prevbizday(dte: date, nd: int = 1, tcs: str | None = None) -> date:
+def prevbizday(
+    dte: Annotated[date, Doc("The reference date")],
+    nd: Annotated[int, Doc("Number of business days to move back")] = 1,
+    tcs: Annotated[str | None, Doc("Comma-separated trading centre codes")] = None,
+) -> date:
+    """Return the date nd business days before dte."""
     return centres(tcs).prevbizday(dte, nd)
 
 
-def nextbizday(dte: date, nd: int = 1, tcs: str | None = None) -> date:
+def nextbizday(
+    dte: Annotated[date, Doc("The reference date")],
+    nd: Annotated[
+        int,
+        Doc("Number of business days to move forward; 0 adjusts to next biz day"),
+    ] = 1,
+    tcs: Annotated[str | None, Doc("Comma-separated trading centre codes")] = None,
+) -> date:
+    """Return the date nd business days after dte."""
     return centres(tcs).nextbizday(dte, nd)
 
 
-def centres(codes: str | None = None) -> TradingCentres:
+def centres(
+    codes: Annotated[
+        str | None, Doc("Comma-separated trading centre codes, e.g. 'LON,NY'")
+    ] = None,
+) -> TradingCentres:
+    """Return a [TradingCentres][ccy.tradingcentres.TradingCentres] instance
+    for the given centre codes."""
     tcs = TradingCentres()
     if codes:
         lcs = codes.upper().replace(" ", "").split(",")
@@ -31,32 +52,44 @@ def centres(codes: str | None = None) -> TradingCentres:
     return tcs
 
 
-@dataclass
-class TradingCentre:
-    code: str
-    calendar: holidays.HolidayBase
+class TradingCentre(BaseModel, arbitrary_types_allowed=True):
+    code: str = Field(description="The code of the trading centre")
+    calendar: holidays.HolidayBase = Field(
+        exclude=True,
+        description="The holiday calendar of the trading centre",
+    )
 
-    def isholiday(self, dte: date) -> bool:
+    def isholiday(self, dte: Annotated[date, Doc("The date to check")]) -> bool:
+        """Return True if the date is a holiday."""
         return dte in self.calendar
 
 
-@dataclass
-class TradingCentres:
-    centres: dict[str, TradingCentre] = field(default_factory=dict)
+class TradingCentres(BaseModel):
+    centres: dict[str, TradingCentre] = Field(default_factory=dict)
 
     @property
     def code(self) -> str:
+        """Comma-separated sorted codes of the trading centres."""
         return ",".join(sorted(self.centres))
 
-    def isbizday(self, dte: date) -> bool:
+    def isbizday(self, dte: Annotated[date, Doc("The date to check")]) -> bool:
+        """Return True if the date is a business day across all centres."""
         if dte.isoweekday() in isoweekend:
             return False
         for c in self.centres.values():
             if c.isholiday(dte):
                 return False
         return True
 
-    def nextbizday(self, dte: date, nd: int = 1) -> date:
+    def nextbizday(
+        self,
+        dte: Annotated[date, Doc("The reference date")],
+        nd: Annotated[
+            int,
+            Doc("Number of business days to move forward; 0 adjusts to next biz day"),
+        ] = 1,
+    ) -> date:
+        """Return the date nd business days after dte."""
         n = 0
         while not self.isbizday(dte):
             dte += oneday
@@ -66,7 +99,12 @@ def nextbizday(self, dte: date, nd: int = 1) -> date:
                 n += 1
         return dte
 
-    def prevbizday(self, dte: date, nd: int = 1) -> date:
+    def prevbizday(
+        self,
+        dte: Annotated[date, Doc("The reference date")],
+        nd: Annotated[int, Doc("Number of business days to move back")] = 1,
+    ) -> date:
+        """Return the date nd business days before dte."""
         n = 0
         if nd < 0:
             return self.nextbizday(dte, -nd)

docs/daycounters.md

@@ -0,0 +1,70 @@
+# Day Counters
+
+The `DayCounter` enum provides standard day count conventions used in financial calculations.
+
+## Available conventions
+
+| Value | Description |
+|-------|-------------|
+| `ACT/360` | Actual days over 360 |
+| `ACT/365` | Actual days over 365 |
+| `30/360` | 30-day months over 360 (US/NASD convention) |
+| `30E/360` | 30-day months over 360 (European convention — end date always capped at 30) |
+| `ACT/ACT` | Actual days over actual days in the year |
+
+## Usage
+
+```python
+from ccy import DayCounter
+from datetime import date
+
+start = date(2024, 1, 1)
+end = date(2024, 7, 1)
+
+dc = DayCounter.ACT360
+print(dc.count(start, end))   # 182.0
+print(dc.dcf(start, end))     # 0.5055...
+```
+
+Instantiate from its string value:
+
+```python
+dc = DayCounter("ACT/365")
+print(dc.dcf(start, end))     # 0.4986...
+```
+
+Iterate over all conventions:
+
+```python
+for dc in DayCounter:
+    print(dc.value, dc.dcf(start, end))
+```
+
+## Methods
+
+### `count(start, end) -> float`
+
+Returns the number of days between two dates. Accepts both `date` and `datetime` objects.
+
+```python
+from datetime import datetime, timezone
+
+start = datetime(2024, 1, 1, 9, 0, tzinfo=timezone.utc)
+end = datetime(2024, 1, 2, 15, 0, tzinfo=timezone.utc)
+
+DayCounter.ACT360.count(start, end)  # 1.25
+```
+
+### `dcf(start, end) -> float`
+
+Returns the day count fraction — the period length expressed as a fraction of a year, according to the convention.
+
+```python
+start = date(2024, 1, 1)
+end = date(2025, 1, 1)
+
+DayCounter.ACT365.dcf(start, end)   # 1.0027... (366 days / 365)
+DayCounter.ACT360.dcf(start, end)   # 1.0166... (366 days / 360)
+DayCounter.ACTACT.dcf(start, end)   # 1.0 (spans exactly one year)
+DayCounter.THIRTY360.dcf(start, end) # 360.0 (30/360 raw result)
+```

docs/index.md

@@ -23,7 +23,8 @@ eur = ccy.currency("aud")
 eur.printinfo()
 ```
 
-a currency object has the following properties:
+A currency object has the following properties:
+
 * *code*: the [ISO 4217](https://en.wikipedia.org/wiki/ISO_4217) three letters code.
 * *twoletterscode*: two letter code.
 * *default_country*: the default [ISO 3166-1 alpha_2](https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2) country code for the currency.