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fastmcp.utilities.versions

Version comparison utilities for component versioning. This module provides utilities for comparing component versions. Versions are strings that are first attempted to be parsed as PEP 440 versions (using the packaging library), falling back to lexicographic string comparison. Examples:
  • “1”, “2”, “10” → parsed as PEP 440, compared semantically (1 < 2 < 10)
  • “1.0”, “2.0” → parsed as PEP 440
  • “v1.0” → ‘v’ prefix stripped, parsed as “1.0”
  • “2025-01-15” → not valid PEP 440, compared as strings
  • None → sorts lowest (unversioned components)

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Functions

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parse_version_key 

parse_version_key(version: str | None) -> VersionKey
Parse a version string into a sortable key. Args:
  • version: The version string, or None for unversioned.
Returns:
  • A VersionKey suitable for sorting.

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version_sort_key 

version_sort_key(component: FastMCPComponent) -> VersionKey
Get a sort key for a component based on its version. Use with sorted() or max() to order components by version. Args:
  • component: The component to get a sort key for.
Returns:
  • A sortable VersionKey.

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compare_versions 

compare_versions(a: str | None, b: str | None) -> int
Compare two version strings. Args:
  • a: First version string (or None).
  • b: Second version string (or None).
Returns:
  • -1 if a < b, 0 if a == b, 1 if a > b.

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is_version_greater 

is_version_greater(a: str | None, b: str | None) -> bool
Check if version a is greater than version b. Args:
  • a: First version string (or None).
  • b: Second version string (or None).
Returns:
  • True if a > b, False otherwise.

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max_version 

max_version(a: str | None, b: str | None) -> str | None
Return the greater of two versions. Args:
  • a: First version string (or None).
  • b: Second version string (or None).
Returns:
  • The greater version, or None if both are None.

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min_version 

min_version(a: str | None, b: str | None) -> str | None
Return the lesser of two versions. Args:
  • a: First version string (or None).
  • b: Second version string (or None).
Returns:
  • The lesser version, or None if both are None.

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Classes

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VersionSpec

Specification for filtering components by version. Used by transforms and providers to filter components to a specific version or version range. Unversioned components (version=None) always match any spec. Args:
  • gte: If set, only versions >= this value match.
  • lt: If set, only versions < this value match.
  • eq: If set, only this exact version matches (gte/lt ignored).
Methods:

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matches 

matches(self, version: str | None) -> bool
Check if a version matches this spec. Args:
  • version: The version to check, or None for unversioned.
Returns:
  • True if the version matches the spec.

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intersect 

intersect(self, other: VersionSpec | None) -> VersionSpec
Return a spec that satisfies both this spec and other. Used by transforms to combine caller constraints with filter constraints. For example, if a VersionFilter has lt=“3.0” and caller requests eq=“1.0”, the intersection validates “1.0” is in range and returns the exact spec. Args:
  • other: Another spec to intersect with, or None.
Returns:
  • A VersionSpec that matches only versions satisfying both specs.

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VersionKey

A comparable version key that handles None, PEP 440 versions, and strings. Comparison order:
  1. None (unversioned) sorts lowest
  2. PEP 440 versions sort by semantic version order
  3. Invalid versions (strings) sort lexicographically
  4. When comparing PEP 440 vs string, PEP 440 comes first