text: import re
  
  from pipgrip.libs.semver.empty_constraint import EmptyConstraint  # noqa:F401
  from pipgrip.libs.semver.patterns import (
      BASIC_CONSTRAINT,
      CARET_CONSTRAINT,
      TILDE_CONSTRAINT,
      TILDE_PEP440_CONSTRAINT,
      X_CONSTRAINT,
  )
  from pipgrip.libs.semver.version import Version
  from pipgrip.libs.semver.version_constraint import VersionConstraint
  from pipgrip.libs.semver.version_range import VersionRange
  from pipgrip.libs.semver.version_union import VersionUnion
  
  __version__ = "0.1.1"
  
  
  def parse_constraint(constraints):  # type: (str) -> VersionConstraint
      if constraints == "*":
          return VersionRange()
  
      or_constraints = re.split(r"\s*\|\|?\s*", constraints.strip())
      or_groups = []
      for constraints in or_constraints:
          and_constraints = re.split(
              "(?<!^)(?<![=>< ,]) *(?<!-)[, ](?!-) *(?!,|$)", constraints
          )
          constraint_objects = []
  
          if len(and_constraints) > 1:
              for constraint in and_constraints:
                  constraint_objects.append(parse_single_constraint(constraint))
          else:
              constraint_objects.append(parse_single_constraint(and_constraints[0]))
  
          if len(constraint_objects) == 1:
              constraint = constraint_objects[0]
          else:
              constraint = constraint_objects[0]
              for next_constraint in constraint_objects[1:]:
                  constraint = constraint.intersect(next_constraint)
  
          or_groups.append(constraint)
  
      if len(or_groups) == 1:
          return or_groups[0]
      else:
          return VersionUnion.of(*or_groups)
  
  
  def parse_single_constraint(constraint):  # type: (str) -> VersionConstraint
      m = re.match(r"(?i)^v?[xX*](\.[xX*])*$", constraint)
      if m:
          return VersionRange()
  
      # Tilde range
      m = TILDE_CONSTRAINT.match(constraint)
      if m:
          version = Version.parse(m.group(1))
  
          high = version.stable.next_minor
          if len(m.group(1).split(".")) == 1:
              high = version.stable.next_major
  
          return VersionRange(
              version, high, include_min=True, always_include_max_prerelease=True
          )
  
      # PEP 440 Tilde range (~=)
      m = TILDE_PEP440_CONSTRAINT.match(constraint)
      if m:
          precision = 1
          if m.group(3):
              precision += 1
  
              if m.group(4):
                  precision += 1
  
          version = Version.parse(m.group(1))
  
          if precision == 2:
              low = version
              high = version.stable.next_major
          else:
              low = version
              high = version.stable.next_minor
  
          return VersionRange(
              low, high, include_min=True, always_include_max_prerelease=True
          )
  
      # Caret range
      m = CARET_CONSTRAINT.match(constraint)
      if m:
          version = Version.parse(m.group(1))
  
          return VersionRange(
              version,
              version.next_breaking,
              include_min=True,
              always_include_max_prerelease=True,
          )
  
      # X Range
      m = X_CONSTRAINT.match(constraint)
      if m:
          op = m.group(1)
          major = int(m.group(2))
          minor = m.group(3)
  
          if minor is not None:
              version = Version(major, int(minor), 0)
  
              result = VersionRange(
                  version,
                  version.next_minor,
                  include_min=True,
                  always_include_max_prerelease=True,
              )
          else:
              if major == 0:
                  result = VersionRange(max=Version(1, 0, 0))
              else:
                  version = Version(major, 0, 0)
  
                  result = VersionRange(
                      version,
                      version.next_major,
                      include_min=True,
                      always_include_max_prerelease=True,
                  )
  
          if op == "!=":
              result = VersionRange().difference(result)
  
          return result
  
      # Basic comparator
      m = BASIC_CONSTRAINT.match(constraint)
      if m:
          op = m.group(1)
          version = m.group(2)
  
          if version == "dev":
              version = "0.0-dev"
  
          try:
              version = Version.parse(version)
          except ValueError:
              raise ValueError(
                  "Could not parse version constraint: {}".format(constraint)
              )
  
          if op == "<":
              return VersionRange(max=version)
          elif op == "<=":
              return VersionRange(max=version, include_max=True)
          elif op == ">":
              return VersionRange(min=version)
          elif op == ">=":
              return VersionRange(min=version, include_min=True)
          elif op == "!=":
              return VersionUnion(VersionRange(max=version), VersionRange(min=version))
          else:
              return version
  
      raise ValueError("Could not parse version constraint: {}".format(constraint))
  