diff --git a/docs/rules.rst b/docs/rules.rst
index 15abe4b..c030c3d 100644
--- a/docs/rules.rst
+++ b/docs/rules.rst
@@ -64,6 +64,12 @@ empty-values
.. automodule:: yamllint.rules.empty_values
+float-values
+------------
+
+.. automodule:: yamllint.rules.float_values
+
+
hyphens
-------
diff --git a/tests/rules/test_float_values.py b/tests/rules/test_float_values.py
new file mode 100644
index 0000000..498daec
--- /dev/null
+++ b/tests/rules/test_float_values.py
@@ -0,0 +1,161 @@
+# Copyright (C) 2022 the yamllint contributors
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see .
+
+from tests.common import RuleTestCase
+
+
+class FloatValuesTestCase(RuleTestCase):
+ rule_id = 'float-values'
+
+ def test_disabled(self):
+ conf = (
+ 'float-values: disable\n'
+ 'new-line-at-end-of-file: disable\n'
+ 'document-start: disable\n'
+ )
+ self.check('angle: 0.0', conf)
+ self.check('angle: .NaN', conf)
+ self.check('angle: .INF', conf)
+ self.check('angle: .1', conf)
+ self.check('angle: 10e-6', conf)
+ self.check(
+ '- &angle .0\n'
+ '- *angle\n',
+ conf,
+ )
+ self.check(
+ '- &angle 10e6\n'
+ '- *angle\n',
+ conf,
+ )
+ self.check(
+ '- &angle .nan\n'
+ '- *angle\n',
+ conf,
+ )
+ self.check(
+ '- &angle .inf\n'
+ '- *angle\n',
+ conf,
+ )
+
+ def test_numeral_before_decimal(self):
+ conf = (
+ 'float-values:\n'
+ ' require-numeral-before-decimal: true\n'
+ ' forbid-scientific-notation: false\n'
+ ' forbid-nan: false\n'
+ ' forbid-inf: false\n'
+ 'new-line-at-end-of-file: disable\n'
+ 'document-start: disable\n'
+ )
+ self.check('angle: .1', conf, problem=(1, 8))
+ self.check('angle: 0.0', conf)
+ self.check('angle: \'.1\'', conf)
+ self.check('angle: !custom_tag 0.0', conf)
+ self.check(
+ '- &angle 0.0\n'
+ '- *angle\n',
+ conf
+ )
+ self.check(
+ '- &angle .0\n'
+ '- *angle\n',
+ conf,
+ problem=(1, 10)
+ )
+
+ def test_scientific_notation(self):
+ conf = (
+ 'float-values:\n'
+ ' require-numeral-before-decimal: false\n'
+ ' forbid-scientific-notation: true\n'
+ ' forbid-nan: false\n'
+ ' forbid-inf: false\n'
+ 'new-line-at-end-of-file: disable\n'
+ 'document-start: disable\n'
+ )
+ self.check('angle: 10e6', conf, problem=(1, 8))
+ self.check('angle: 10e-6', conf, problem=(1, 8))
+ self.check('angle: 0.00001', conf)
+ self.check('angle: \'10e-6\'', conf)
+ self.check('angle: !custom_tag 10e-6', conf)
+ self.check(
+ '- &angle 0.000001\n'
+ '- *angle\n',
+ conf
+ )
+ self.check(
+ '- &angle 10e-6\n'
+ '- *angle\n',
+ conf,
+ problem=(1, 10)
+ )
+ self.check(
+ '- &angle 10e6\n'
+ '- *angle\n',
+ conf,
+ problem=(1, 10)
+ )
+
+ def test_nan(self):
+ conf = (
+ 'float-values:\n'
+ ' require-numeral-before-decimal: false\n'
+ ' forbid-scientific-notation: false\n'
+ ' forbid-nan: true\n'
+ ' forbid-inf: false\n'
+ 'new-line-at-end-of-file: disable\n'
+ 'document-start: disable\n'
+ )
+ self.check('angle: .NaN', conf, problem=(1, 8))
+ self.check('angle: .NAN', conf, problem=(1, 8))
+ self.check('angle: \'.NaN\'', conf)
+ self.check('angle: !custom_tag .NaN', conf)
+ self.check(
+ '- &angle .nan\n'
+ '- *angle\n',
+ conf,
+ problem=(1, 10)
+ )
+
+ def test_inf(self):
+ conf = (
+ 'float-values:\n'
+ ' require-numeral-before-decimal: false\n'
+ ' forbid-scientific-notation: false\n'
+ ' forbid-nan: false\n'
+ ' forbid-inf: true\n'
+ 'new-line-at-end-of-file: disable\n'
+ 'document-start: disable\n'
+ )
+ self.check('angle: .inf', conf, problem=(1, 8))
+ self.check('angle: .INF', conf, problem=(1, 8))
+ self.check('angle: -.inf', conf, problem=(1, 8))
+ self.check('angle: -.INF', conf, problem=(1, 8))
+ self.check('angle: \'.inf\'', conf)
+ self.check('angle: !custom_tag .inf', conf)
+ self.check(
+ '- &angle .inf\n'
+ '- *angle\n',
+ conf,
+ problem=(1, 10)
+ )
+ self.check(
+ '- &angle -.inf\n'
+ '- *angle\n',
+ conf,
+ problem=(1, 10)
+ )
diff --git a/yamllint/conf/default.yaml b/yamllint/conf/default.yaml
index 0720ded..0dea0aa 100644
--- a/yamllint/conf/default.yaml
+++ b/yamllint/conf/default.yaml
@@ -19,6 +19,7 @@ rules:
level: warning
empty-lines: enable
empty-values: disable
+ float-values: disable
hyphens: enable
indentation: enable
key-duplicates: enable
diff --git a/yamllint/rules/__init__.py b/yamllint/rules/__init__.py
index f83f1f3..5a4fe81 100644
--- a/yamllint/rules/__init__.py
+++ b/yamllint/rules/__init__.py
@@ -32,6 +32,7 @@ from yamllint.rules import (
new_line_at_end_of_file,
new_lines,
octal_values,
+ float_values,
quoted_strings,
trailing_spaces,
truthy,
@@ -48,6 +49,7 @@ _RULES = {
document_start.ID: document_start,
empty_lines.ID: empty_lines,
empty_values.ID: empty_values,
+ float_values.ID: float_values,
hyphens.ID: hyphens,
indentation.ID: indentation,
key_duplicates.ID: key_duplicates,
diff --git a/yamllint/rules/float_values.py b/yamllint/rules/float_values.py
new file mode 100644
index 0000000..6a80bb9
--- /dev/null
+++ b/yamllint/rules/float_values.py
@@ -0,0 +1,158 @@
+# Copyright (C) 2022 the yamllint contributors
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see .
+
+"""
+Use this rule to limit the permitted values for floating-point numbers.
+YAML permits three classes of float expressions: approximation to real numbers,
+positive and negative infinity and "not a number".
+
+.. rubric:: Options
+
+* Use ``require-numeral-before-decimal`` to require floats to start
+ with a numeral (ex ``0.0`` instead of ``.0``).
+* Use ``forbid-scientific-notation`` to forbid scientific notation.
+* Use ``forbid-nan`` to forbid NaN (not a number) values.
+* Use ``forbid-inf`` to forbid infinite values.
+
+.. rubric:: Default values (when enabled)
+
+.. code-block:: yaml
+
+ rules:
+ float-values:
+ forbid-inf: false
+ forbid-nan: false
+ forbid-scientific-notation: false
+ require-numeral-before-decimal: false
+
+.. rubric:: Examples
+
+#. With ``float-values: {require-numeral-before-decimal: true}``
+
+ the following code snippets would **PASS**:
+ ::
+
+ anemometer:
+ angle: 0.0
+
+ the following code snippets would **FAIL**:
+ ::
+
+ anemometer:
+ angle: .0
+
+#. With ``float-values: {forbid-scientific-notation: true}``
+
+ the following code snippets would **PASS**:
+ ::
+
+ anemometer:
+ angle: 0.00001
+
+ the following code snippets would **FAIL**:
+ ::
+
+ anemometer:
+ angle: 10e-6
+
+#. With ``float-values: {forbid-nan: true}``
+
+ the following code snippets would **FAIL**:
+ ::
+
+ anemometer:
+ angle: .NaN
+
+ #. With ``float-values: {forbid-inf: true}``
+
+ the following code snippets would **FAIL**:
+ ::
+
+ anemometer:
+ angle: .inf
+"""
+
+import re
+
+import yaml
+
+from yamllint.linter import LintProblem
+
+
+ID = 'float-values'
+TYPE = 'token'
+CONF = {
+ 'require-numeral-before-decimal': bool,
+ 'forbid-scientific-notation': bool,
+ 'forbid-nan': bool,
+ 'forbid-inf': bool,
+}
+DEFAULT = {
+ 'require-numeral-before-decimal': False,
+ 'forbid-scientific-notation': False,
+ 'forbid-nan': False,
+ 'forbid-inf': False,
+}
+
+IS_NUMERAL_BEFORE_DECIMAL_PATTERN = (
+ re.compile('[-+]?(\\.[0-9]+)([eE][-+]?[0-9]+)?')
+)
+IS_SCIENTIFIC_NOTATION_PATTERN = re.compile(
+ '[-+]?(\\.[0-9]+|[0-9]+(\\.[0-9]*)?)([eE][-+]?[0-9]+)'
+)
+IS_INF_PATTERN = re.compile('[-+]?(\\.inf|\\.Inf|\\.INF)')
+IS_NAN_PATTERN = re.compile('\\.nan|\\.NaN|\\.NAN')
+
+
+def check(conf, token, prev, next, nextnext, context):
+ if prev and isinstance(prev, yaml.tokens.TagToken):
+ return
+ if not isinstance(token, yaml.tokens.ScalarToken):
+ return
+ if token.style:
+ return
+ val = token.value
+
+ if conf['forbid-nan'] and IS_NAN_PATTERN.match(val):
+ yield LintProblem(
+ token.start_mark.line + 1,
+ token.start_mark.column + 1,
+ 'forbidden not a number value "%s"' % token.value,
+ )
+
+ if conf['forbid-inf'] and IS_INF_PATTERN.match(val):
+ yield LintProblem(
+ token.start_mark.line + 1,
+ token.start_mark.column + 1,
+ f"forbidden infinite value {token.value}",
+ )
+
+ if conf[
+ 'forbid-scientific-notation'
+ ] and IS_SCIENTIFIC_NOTATION_PATTERN.match(val):
+ yield LintProblem(
+ token.start_mark.line + 1,
+ token.start_mark.column + 1,
+ f"forbidden scientific notation {token.value}",
+ )
+
+ if conf[
+ 'require-numeral-before-decimal'
+ ] and IS_NUMERAL_BEFORE_DECIMAL_PATTERN.match(val):
+ yield LintProblem(
+ token.start_mark.line + 1,
+ token.start_mark.column + 1,
+ f"forbidden decimal missing 0 prefix {token.value}",
+ )