计数器

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。

具体来说，它允许实现函数访问当前目标的标签、属性、配置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

actions ctx.actions

包含用于声明输出文件的方法以及用于生成输出文件的操作。

aspect_ids

list ctx.aspect_ids

应用于目标的所有方面 ID 的列表。仅在 aspect 实现函数中可用。

attr

struct ctx.attr

用于访问特性值的结构体。值由用户提供（如果未提供，则使用默认值）。结构体的属性及其值的类型与提供给 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

与 bin 目录对应的根目录。

build_file_path

string ctx.build_file_path

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

实验性功能。此字段目前处于实验阶段，随时可能会发生变化。请勿依赖此行为。

当前目标表示的 build 设置的值。对于未在规则定义中设置 build_setting 属性的规则，访问此字段会发生错误。

配置

configuration ctx.configuration

默认配置。如需了解详情，请参阅配置类型。

coverage_instrumented

bool ctx.coverage_instrumented(target=None)

返回是否应在执行此规则或（如果提供了 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 Target; or 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()

对于将 _skylark_testable 设为 True 的规则，此方法会返回一个 Actions 提供程序，表示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。

default_provider

Provider ctx.default_provider

已弃用。请改用 DefaultInfo。

disabled_features

list ctx.disabled_features

用户针对此规则明确停用的一组功能。

exec_groups

ExecGroupCollection ctx.exec_groups

适用于此规则的执行组的集合，按名称编入索引。使用 ctx.exec_groups[name_of_group] 访问。

可执行文件

struct ctx.executable

一个包含可执行文件（在标记为 executable=True 的标签类型属性中定义的）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=[], short_paths=False)

通过将 $(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。扩展仅适用于指向此规则的直接依赖项的标签或可选参数 targets 中明确列出的标签。

如果引用的目标有多个输出，则 $(location ...) 会导致错误。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

参数 说明
input 必需
要展开的字符串。
targets sequence of Targets; default = []
用于查询更多信息的目标列表。
short_paths default = False
使用相对于根目录的路径，而不是完整的执行路径
可能会返回 None。

expand_make_variables

string ctx.expand_make_variables(attribute_name, command, additional_substitutions)

已弃用。请改用 ctx.var 访问变量。
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
            
            
                                     required

                          The attribute name. Used for error reporting.
            		
          

                  

            
              command
            
            
                                     required

                          The expression to expand. It can contain references to "Make variables".
            		
          

                  

            
              additional_substitutions
            
            
                                     required

                          Additional substitutions to make beyond the default make variables.
            		
          

                
      


        
features

        
list ctx.features


    The set of features that are explicitly enabled by the user for this rule. See example of use.


        
file

        
struct ctx.file


    A struct containing files defined in label type attributes marked as allow_single_file. The struct fields correspond to the attribute names. The struct value is always a File or None. If an optional attribute is not specified in the rule then the corresponding struct value is None. If a label type is not marked as allow_single_file, no corresponding struct field is generated. It is a shortcut for:
list(ctx.attr.<ATTR>.files)[0]
In other words, use file to access the (singular) default output of a dependency. See example of use.


        
files

        
struct ctx.files


    A struct containing files defined in label or label list type attributes. The struct fields correspond to the attribute names. The struct values are list of Files.  It is a shortcut for:
[f for t in ctx.attr.<ATTR> for f in t.files]
 In other words, use files to access the default outputs of a dependency. See example of use.


        
fragments

        
fragments ctx.fragments


    Allows access to configuration fragments in target configuration.


        
genfiles_dir

        
root ctx.genfiles_dir


    The root corresponding to genfiles directory.


        
host_configuration

        
configuration ctx.host_configuration


    The host configuration. See the configuration type for more details.


        
host_fragments

        
fragments ctx.host_fragments


    Allows access to configuration fragments in host configuration.


        
info_file

        
File ctx.info_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.


        
label

        
Label ctx.label


    The label of the target currently being analyzed.


        
new_file

        
File ctx.new_file(var1, var2=unbound, var3=unbound)


    DEPRECATED. Use ctx.actions.declare_file. 
Creates a file object. There are four possible signatures to this method:
  • new_file(filename): Creates a file object with the given filename in the current package.
  • new_file(file_root, filename): Creates a file object with the given filename under the given file root.
  • new_file(sibling_file, filename): Creates a file object in the same directory as the given sibling file.
  • new_file(file_root, sibling_file, suffix): Creates a file object with same base name of the sibling_file but with different given suffix, under the given file root.
 
Does not actually create a file on the file system, just declares that some action will do so. You must create an action that generates the file. If the file should be visible to other rules, declare a rule output instead when possible. Doing so enables Blaze to associate a label with the file that rules can refer to (allowing finer dependency control) instead of referencing the whole rule.

          
      
Parameters

      

        
          
          
        
        
          

            Parameter
            Description
          

        
        
                  

            
              var1
            
            
                          string; or root; or File;
                                     required


            		
          

                  

            
              var2
            
            
                          string; or File;
                                     default = unbound


            		
          

                  

            
              var3
            
            
                          string;
                                     default = unbound


            		
          

                
      


        
outputs

        
structure ctx.outputs


    A pseudo-struct containing all the predeclared output files, represented by File 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 corresponding File.
  • 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 corresponding File; otherwise the field value is None.
  • 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 of File 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 or test, 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 the executable arg of DefaultInfo.



        
resolve_command

        
tuple ctx.resolve_command(command='', attribute=None, expand_locations=False, make_variables=None, tools=[], label_dict={}, execution_requirements={})


    (Experimental) Returns a tuple (inputs, command, input_manifests) of the list of resolved inputs, the argv list for the resolved command, and the runfiles metadata required to run the command, all 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).

          
      
Parameters

      

        
          
          
        
        
          

            Parameter
            Description
          

        
        
                  

            
              command
            
            
                                     default = ''

                          Command to resolve.
            		
          

                  

            
              attribute
            
            
                          string; or None;
                                     default = None

                          Name of the associated attribute for which to issue an error, or None.
            		
          

                  

            
              expand_locations
            
            
                                     default = False

                          Shall we expand $(location) variables? See ctx.expand_location() for more details.
            		
          

                  

            
              make_variables
            
            
                          dict; or None;
                                     default = None

                          Make variables to expand, or None.
            		
          

                  

            
              tools
            
            
                          sequence of Targets;
                                     default = []

                          List of tools (list of targets).
            		
          

                  

            
              label_dict
            
            
                                     default = {}

                          Dictionary of resolved labels and the corresponding list of Files (a dict of Label : list of Files).
            		
          

                  

            
              execution_requirements
            
            
                                     default = {}

                          Information for scheduling the action to resolve this command. See tags for useful keys.
            		
          

                
      


        
resolve_tools

        
tuple ctx.resolve_tools(tools=[])


    Returns a tuple (inputs, input_manifests) of the depset of resolved inputs and the runfiles metadata required to run the tools, both of them suitable for passing as the same-named arguments of the ctx.actions.run method.

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.

          
      
Parameters

      

        
          
          
        
        
          

            Parameter
            Description
          

        
        
                  

            
              tools
            
            
                          sequence of Targets;
                                     default = []

                          List of tools (list of targets).
            		
          

                
      


        
rule

        
rule_attributes ctx.rule


    Rule attributes descriptor for the rule that the aspect is applied to. Only available in aspect implementation functions.


        
runfiles

        
runfiles ctx.runfiles(files=[], transitive_files=None, collect_data=False, collect_default=False, symlinks={}, root_symlinks={})


    Creates a runfiles object.

          
      
Parameters

      

        
          
          
        
        
          

            Parameter
            Description
          

        
        
                  

            
              files
            
            
                          sequence of Files;
                                     default = []

                          The list of files to be added to the runfiles.
            		
          

                  

            
              transitive_files
            
            
                          depset of Files; or None;
                                     default = 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
            
            
                                     default = 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
            
            
                                     default = 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.
            

          

                  

            
            
                          dict; or depset of SymlinkEntrys;
                                     default = {}

                          Either a SymlinkEntry depset or the map of symlinks, prefixed by workspace name, to be added to the runfiles. See Runfiles symlinks in the rules guide.
            		
          

                  

            
            
                          dict; or depset of SymlinkEntrys;
                                     default = {}

                          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


    A struct to access the values of attributes with split configurations. If the attribute is a label list, the value of split_attr is a dict of the keys of the split (as strings) to lists of the ConfiguredTargets in that branch of the split. If the attribute is a label, then the value of split_attr is a dict of the keys of the split (as strings) to single ConfiguredTargets. Attributes with split configurations still appear in the attr struct, but their values will be single lists with all the branches of the split merged together.


        
target_platform_has_constraint

        
bool ctx.target_platform_has_constraint(constraintValue)


    Returns true if the given constraint value is part of the current target platform.

          
      
Parameters

      

        
          
          
        
        
          

            Parameter
            Description
          

        
        
                  

            
              constraintValue
            
            
                                     required

                          The constraint value to check the target platform against.
            		
          

                
      


        
toolchains

        
ToolchainContext ctx.toolchains


    Toolchains for the default exec group of this rule.


        
var

        
dict ctx.var


    Dictionary (String to String) of configuration variables.


        
version_file

        
File ctx.version_file


    The file that is used to hold the volatile workspace status for the current build request. See documentation for --workspace_status_command for more information.


        
workspace_name

        
string ctx.workspace_name


    The workspace name as defined in the WORKSPACE file.