传递给规则或方面实现函数的上下文对象。它提供分析当前目标所需的信息和方法。
具体而言,它可让实现函数访问当前目标的标签、属性、配置以及其依赖项的提供程序。它提供了用于声明输出文件及其生成操作的方法。
上下文对象在调用实现函数的整个过程中有效。在其关联的函数之外访问这些对象没有用处。如需了解详情,请参阅“规则”页面。
成员
- 操作
- aspect_ids
- attr
- bin_dir
- build_file_path
- build_setting_value
- 配置
- coverage_instrumented
- created_actions
- disabled_features
- exec_groups
- executable
- expand_location
- expand_make_variables
- 功能
- file
- 文件
- fragment
- genfiles_dir
- info_file
- label
- 输出
- resolve_command
- resolve_tools
- rule
- runfiles
- split_attr
- super
- target_platform_has_constraint
- 工具链
- var
- version_file
- workspace_name
操作
actions ctx.actions
aspect_ids
list ctx.aspect_ids
属性
struct ctx.attr
rule
函数的 attrs
字典的键和值相对应。查看使用示例。
bin_dir
root ctx.bin_dir
build_file_path
string ctx.build_file_path
ctx.label.package + '/BUILD'
。此规则的 BUILD 文件的路径(相对于源代码根目录)。
build_setting_value
unknown ctx.build_setting_value
build_setting
属性的规则实例的上下文,则读取此内容会出错。
配置
configuration ctx.configuration
coverage_instrumented
bool ctx.coverage_instrumented(target=None)
target
)该目标指定的规则的编译操作时生成代码覆盖率插桩。(如果提供的不是规则,而是 Starlark 规则目标,则此值会返回 False。)根据 --instrumentation_filter 和 --instrument_test_targets 配置设置,检查当前规则的来源(如果未提供目标)或目标的来源是否应进行插桩。这与 coverage_enabled
的配置不同,后者用于记录是否为整个运行启用了覆盖率数据收集,但不用于记录是否应对特定目标进行插桩。
参数
参数 | 说明 |
---|---|
target
|
目标;或 None ;
默认值为 None 指定规则的目标。如果未提供,则默认为当前规则。 |
created_actions
StarlarkValue ctx.created_actions()
True
的规则,此方法会返回一个 Actions
提供程序,表示目前为止为当前规则创建的所有操作。对于所有其他规则,返回 None
。请注意,创建后续操作时,提供程序不会更新,因此如果您想检查这些操作,则必须再次调用此函数。这有助于为规则实现辅助函数编写测试,这些函数可能会接受
ctx
对象并对其创建操作。
disabled_features
list ctx.disabled_features
exec_groups
ExecGroupCollection ctx.exec_groups
ctx.exec_groups[name_of_group]
访问。
可执行文件
struct ctx.executable
executable=True
的可执行文件的 struct
。结构体字段与属性名称相对应。结构体中的每个值都是 File
或 None
。如果规则中未指定可选属性,则相应的结构体值为 None
。如果标签类型未标记为 executable=True
,则系统不会生成相应的结构体字段。查看使用示例。
expand_location
string ctx.expand_location(input, targets=[])
$(location //x)
替换为目标 //x 的输出文件的路径,展开给定字符串中的所有 $(location ...)
模板。展开功能仅适用于指向此规则的直接依赖项或在可选参数 targets
中明确列出的标签。如果引用的目标具有多个输出,$(location ...)
将导致错误。在这种情况下,请使用 $(locations ...)
,因为它会生成以空格分隔的输出路径列表。它也可以安全地用于单个输出文件。此函数非常适合让用户在 BUILD 文件中指定命令(例如
genrule
)。在其他情况下,直接操作标签通常更好。
参数
可以返回None
。
expand_make_variables
string ctx.expand_make_variables(attribute_name, command, additional_substitutions)
在将所有引用展开为“Make 变量”后,返回一个字符串。变量必须采用以下格式:
$(VAR_NAME)
。此外,$$VAR_NAME
expands to $VAR_NAME
. Examples:ctx.expand_make_variables("cmd", "$(MY_VAR)", {"MY_VAR": "Hi"}) # == "Hi" ctx.expand_make_variables("cmd", "$$PWD", {}) # == "$PWD" Additional variables may come from other places, such as configurations. Note that this function is experimental.Parameters
Parameter Description attribute_name
string; required
The attribute name. Used for error reporting.command
string; required
The expression to expand. It can contain references to "Make variables".additional_substitutions
dict; required
Additional substitutions to make beyond the default make variables.features
The set of features that are explicitly enabled by the user for this rule. See example of use. list ctx.featuresfile
A struct ctx.filestruct
containing files defined in label type attributes marked asallow_single_file
. The struct fields correspond to the attribute names. The struct value is always aFile
orNone
. If an optional attribute is not specified in the rule then the corresponding struct value isNone
. If a label type is not marked asallow_single_file
, no corresponding struct field is generated. It is a shortcut for:In other words, use list(ctx.attr.<ATTR>.files)[0]file
to access the (singular) default output of a dependency. See example of use.files
A struct ctx.filesstruct
containing files defined in label or label list type attributes. The struct fields correspond to the attribute names. The struct values arelist
ofFile
s. It is a shortcut for:In other words, use [f for t in ctx.attr.<ATTR> for f in t.files]files
to access the default outputs of a dependency. See example of use.fragments
Allows access to configuration fragments in target configuration. fragments ctx.fragmentsgenfiles_dir
The root corresponding to genfiles directory. root ctx.genfiles_dirinfo_file
The file that is used to hold the non-volatile workspace status for the current build request. See documentation for --workspace_status_command for more information. File ctx.info_filelabel
The label of the target currently being analyzed. Label ctx.labeloutputs
A pseudo-struct containing all the predeclared output files, represented by structure ctx.outputsFile
objects. See the Rules page for more information and examples.This field does not exist on aspect contexts, since aspects do not have predeclared outputs.
The fields of this object are defined as follows. It is an error if two outputs produce the same field name or have the same label.
- If the rule declares an
outputs
dict, then for every entry in the dict, there is a field whose name is the key and whose value is the correspondingFile
. - For every attribute of type
attr.output
that the rule declares, there is a field whose name is the attribute's name. If the target specified a label for that attribute, then the field value is the correspondingFile
; otherwise the field value isNone
. - For every attribute of type
attr.output_list
that the rule declares, there is a field whose name is the attribute's name. The field value is a list ofFile
objects corresponding to the labels given for that attribute in the target, or an empty list if the attribute was not specified in the target. - (Deprecated) If the rule is marked
executable
ortest
, there is a field named"executable"
, which is the default executable. It is recommended that instead of using this, you pass another file (either predeclared or not) to theexecutable
arg ofDefaultInfo
.
resolve_command
tuple ctx.resolve_command(command='', attribute=None, expand_locations=False, make_variables=None, tools=[], label_dict={}, execution_requirements={})
(inputs, command, empty list)
of the list of resolved inputs and the argv list for the resolved command both of them suitable for passing as the same-named arguments of the ctx.action
method.Note for Windows users: this method requires Bash (MSYS2). Consider using
resolve_tools()
instead (if that fits your needs). The empty list is returned as the third member of the tuple for backwards compatibility.
Parameters
Parameter | Description |
---|---|
command
|
string;
default is '' Command to resolve. |
attribute
|
string; or None ;
default is None Name of the associated attribute for which to issue an error, or None. |
expand_locations
|
bool;
default is False Shall we expand $(location) variables? See ctx.expand_location() for more details. |
make_variables
|
dict; or None ;
default is None Make variables to expand, or None. |
tools
|
sequence of Targets;
default is [] List of tools (list of targets). |
label_dict
|
dict;
default is {} Dictionary of resolved labels and the corresponding list of Files (a dict of Label : list of Files). |
execution_requirements
|
dict;
default is {} Information for scheduling the action to resolve this command. See tags for useful keys. |
resolve_tools
tuple ctx.resolve_tools(tools=[])
(inputs, empty list)
of the depset of resolved inputs required to run the tools, suitable for passing as the same-named argument of the ctx.actions.run
and ctx.actions.run_shell
methods. In contrast to
ctx.resolve_command
, this method does not require that Bash be installed on the machine, so it's suitable for rules built on Windows. The empty list is returned as part of the tuple for backward compatibility.
Parameters
rule
rule_attributes ctx.rule
runfiles
runfiles ctx.runfiles(files=[], transitive_files=None, collect_data=False, collect_default=False, symlinks={}, root_symlinks={})
Parameters
Parameter | Description |
---|---|
files
|
sequence of Files;
default is [] The list of files to be added to the runfiles. |
transitive_files
|
depset of Files; or None ;
default is None The (transitive) set of files to be added to the runfiles. The depset should use the default order (which, as the name implies, is the default).
|
collect_data
|
bool;
default is False Use of this parameter is not recommended. See runfiles guide. Whether to collect the data runfiles from the dependencies in srcs, data and deps attributes. |
collect_default
|
bool;
default is False Use of this parameter is not recommended. See runfiles guide. Whether to collect the default runfiles from the dependencies in srcs, data and deps attributes. |
symlinks
|
dict; or depset of SymlinkEntrys;
default is {} Either a SymlinkEntry depset or the map of symlinks to be added to the runfiles. Symlinks are always added under the main workspace's runfiles directory (e.g. <runfiles_root>/_main/<symlink_path> , not the directory corresponding to the current target's repository. See Runfiles symlinks in the rules guide.
|
root_symlinks
|
dict; or depset of SymlinkEntrys;
default is {} Either a SymlinkEntry depset or a map of symlinks to be added to the runfiles. See Runfiles symlinks in the rules guide. |
split_attr
struct ctx.split_attr
super
unknown ctx.super()
target_platform_has_constraint
bool ctx.target_platform_has_constraint(constraintValue)
Parameters
Parameter | Description |
---|---|
constraintValue
|
ConstraintValueInfo;
required The constraint value to check the target platform against. |
toolchains
ToolchainContext ctx.toolchains
var
dict ctx.var
version_file
File ctx.version_file
workspace_name
string ctx.workspace_name
--enable_bzlmod
is on, this is the fixed string _main
. Otherwise, this is the workspace name as defined in the WORKSPACE file.