Class: Generator

Blockly.Generator

class   static

Constructor

Generator

new Generator(name)

Class for a code generator that translates the blocks into a language.

Parameter
name	string Language name of this generator.

Properties

COMMENT_WRAP

number

Maximum length for a comment before wrapping. Does not account for indenting level.

definitions_

protected

(non-null Object or undefined)

A dictionary of definitions to be printed before the code.

FUNCTION_NAME_PLACEHOLDER_

protected

string

This is used as a placeholder in functions defined using Blockly.Generator.provideFunction_. It must not be legal code that could legitimately appear in a function definition (or comment), and it must not confuse the regular expression parser.

functionNames_

protected

(non-null Object or undefined)

A dictionary mapping desired function names in definitions_ to actual function names (to avoid collisions with user functions).

INDENT

string

The method of indenting. Defaults to two spaces, but language generators may override this to increase indent or change to tabs.

INFINITE_LOOP_TRAP

nullable string

Arbitrary code to inject into locations that risk causing infinite loops. Any instances of '%1' will be replaced by the block ID that failed. E.g. ' checkTimeout(%1);\n'

isInitialized

nullable boolean

Whether the init method has been called. Generators that set this flag to false after creation and true in init will cause blockToCode to emit a warning if the generator has not been initialized. If this flag is untouched, it will have no effect.

nameDB_

protected

(non-null Blockly.Names or undefined)

A database of variable and procedure names.

ORDER_OVERRIDES

non-null Array of non-null Array of number

List of outer-inner pairings that do NOT require parentheses.

RESERVED_WORDS_

protected

string

Comma-separated list of reserved words.

STATEMENT_PREFIX

nullable string

Arbitrary code to inject before every statement. Any instances of '%1' will be replaced by the block ID of the statement. E.g. 'highlight(%1);\n'

STATEMENT_SUFFIX

nullable string

Arbitrary code to inject after every statement. Any instances of '%1' will be replaced by the block ID of the statement. E.g. 'highlight(%1);\n'

Methods

addLoopTrap

addLoopTrap(branch, block) returns string

Add an infinite loop trap to the contents of a loop. Add statement suffix at the start of the loop block (right after the loop statement executes), and a statement prefix to the end of the loop block (right before the loop statement executes).

Parameter
branch	string Code for loop contents.
block	Blockly.Block Enclosing block. Value must not be null.

Returns

string Loop contents, with infinite loop trap added.

addReservedWords

addReservedWords(words)

Add one or more words to the list of reserved words for this language.

Parameter
words	string Comma-separated list of words to add to the list. No spaces. Duplicates are ok.

allNestedComments

allNestedComments(block) returns string

Recursively spider a tree of blocks, returning all their comments.

Parameter
block	Blockly.Block The block from which to start spidering. Value must not be null.

Returns

string Concatenated list of comments.

blockToCode

blockToCode(block, opt_thisOnly) returns (string or Array)

Generate code for the specified block (and attached blocks). The generator must be initialized before calling this function.

Parameter
block	Blockly.Block The block to generate code for.
opt_thisOnly	Optional boolean True to generate code for only this statement.

Returns

(string or non-null Array) For statement blocks, the generated code. For value blocks, an array containing the generated code and an operator order value. Returns '' if block is null.

finish

finish(code) returns string

Hook for code to run at end of code generation. Subclasses may override this, e.g. to prepend the generated code with import statements or variable definitions.

Parameter
code	string Generated code.

Returns

string Completed code.

init

init(_workspace)

Hook for code to run before code generation starts. Subclasses may override this, e.g. to initialise the database of variable names.

Parameter
_workspace	Blockly.Workspace Workspace to generate code from. Value must not be null.

injectId

injectId(msg, block) returns string

Inject a block ID into a message to replace '%1'. Used for STATEMENT_PREFIX, STATEMENT_SUFFIX, and INFINITE_LOOP_TRAP.

Parameter
msg	string Code snippet with '%1'.
block	Blockly.Block Block which has an ID. Value must not be null.

Returns

string Code snippet with ID.

prefixLines

prefixLines(text, prefix) returns string

Prepend a common prefix onto each line of code. Intended for indenting code or adding comment markers.

Parameter
text	string The lines of code.
prefix	string The common prefix.

Returns

string The prefixed lines of code.

provideFunction_

protected

provideFunction_(desiredName, code) returns string

Define a developer-defined function (not a user-defined procedure) to be included in the generated code. Used for creating private helper functions. The first time this is called with a given desiredName, the code is saved and an actual name is generated. Subsequent calls with the same desiredName have no effect but have the same return value.

It is up to the caller to make sure the same desiredName is not used for different helper functions (e.g. use "colourRandom" and "listRandom", not "random"). There is no danger of colliding with reserved words, or user-defined variable or procedure names.

The code gets output when Blockly.Generator.finish() is called.

Parameter
desiredName	string The desired name of the function (e.g. mathIsPrime).
code	Array of string A list of statements. Use ' ' for indents. Value must not be null.

Returns

string The actual name of the new function. This may differ from desiredName if the former has already been taken by the user.

scrub_

protected

scrub_(_block, code, _opt_thisOnly) returns string

Common tasks for generating code from blocks. This is called from blockToCode and is called on every block, not just top level blocks. Subclasses may override this, e.g. to generate code for statements following the block, or to handle comments for the specified block and any connected value blocks.

Parameter
_block	Blockly.Block The current block. Value must not be null.
code	string The code created for this block.
_opt_thisOnly	Optional boolean True to generate code for only this statement.

Returns

string Code with comments and subsequent blocks added.

scrubNakedValue

scrubNakedValue(line) returns string

Naked values are top-level blocks with outputs that aren't plugged into anything. Subclasses may override this, e.g. if their language does not allow naked values.

Parameter
line	string Line of generated code.

Returns

string Legal line of code.

statementToCode

statementToCode(block, name) returns string

Generate a code string representing the blocks attached to the named statement input. Indent the code. This is mainly used in generators. When trying to generate code to evaluate look at using workspaceToCode or blockToCode.

Parameter
block	Blockly.Block The block containing the input. Value must not be null.
name	string The name of the input.

Returns

string Generated code or '' if no blocks are connected.

valueToCode

valueToCode(block, name, outerOrder) returns string

Generate code representing the specified value input.

Parameter
block	Blockly.Block The block containing the input. Value must not be null.
name	string The name of the input.
outerOrder	number The maximum binding strength (minimum order value) of any operators adjacent to "block".

Returns

string Generated code or '' if no blocks are connected or the specified input does not exist.

workspaceToCode

workspaceToCode(workspace) returns string

Generate code for all blocks in the workspace to the specified language.

Parameter
workspace	Optional Blockly.Workspace Workspace to generate code from. Value must not be null.

Returns

string Generated code.