public abstract class AbstractCodeWriter<T extends AbstractCodeWriter<T>>
extends java.lang.Object
An AbstractCodeWriter can be used to write basically any kind of code, including whitespace sensitive and brace-based.
The following example generates some Python code:
SimpleCodeWriter writer = new SimpleCodeWriter();
writer.write("def Foo(str):")
.indent()
.write("print str");
String code = writer.toString();
The write(java.lang.Object, java.lang.Object...)
, openBlock(java.lang.String, java.lang.Object...)
, and closeBlock(java.lang.String, java.lang.Object...)
methods
take a code expression and a variadic list of arguments that are
interpolated into the expression. Consider the following call to
write
:
SimpleCodeWriter = new SimpleCodeWriter();
writer.write("Hello, $L", "there!");
String code = writer.toString();
In the above example, $L
is interpolated and replaced with the
relative argument there!
.
An AbstractCodeWriter supports three kinds of interpolations: relative, positional, and named. Each of these kinds of interpolations pass a value to a formatter.
Formatters are named functions that accept an object as input, accepts a
string that contains the current indentation (it can be ignored if not useful),
and returns a string as output. AbstractCodeWriter
registers two built-in
formatters:
L
(literal): Outputs a literal value of an Object
using
the following implementation: (1) A null value is formatted as "".
(2) An empty Optional
value is formatted as "". (3) A non-empty
Optional
value is recursively formatted using the value inside
of the Optional
. (3) All other valeus are formatted using the
result of calling String.valueOf(java.lang.Object)
.C
(call): Runs a Runnable
or Consumer
argument
that is expected to write to the same writer. Any text written to the AbstractCodeWriter
inside of the Runnable is used as the value of the argument. Note that a
single trailing newline is removed from the captured text. If a Runnable is
provided, it is required to have a reference to the AbstractCodeWriter. A Consumer
is provided a reference to the AbstractCodeWriter as a single argument.
SimpleCodeWriter writer = new SimpleCodeWriter();
writer.write("Hello, $C.", () -> writer.write("there"));
assert(writer.toString().equals("Hello, there.\n"));
S
(string): Adds double quotes around the result of formatting a
value first using the default literal "L" implementation described
above and then wrapping the value in an escaped string safe for use in
Java according to https://docs.oracle.com/javase/specs/jls/se7/html/jls-3.html#jls-3.10.6.
This formatter can be overridden if needed to support other
programming languages.Custom formatters can be registered using putFormatter(char, java.util.function.BiFunction<java.lang.Object, java.lang.String, java.lang.String>)
. Custom
formatters can be used only within the state they were added. Because states
inherit the formatters of parent states, adding a formatter to the root state
of the AbstractCodeWriter allows the formatter to be used in any state.
The identifier given to a formatter must match one of the following characters:
"!" / "#" / "%" / "&" / "*" / "+" / "," / "-" / "." / "/" / ";" / "=" / "?" / "@" / "A" / "B" / "C" / "D" / "E" / "F" / "G" / "H" / "I" / "J" / "K" / "L" / "M" / "N" / "O" / "P" / "Q" / "R" / "S" / "T" / "U" / "V" / "W" / "X" / "Y" / "Z" / "^" / "_" / "`" / "~"
Placeholders in the form of "$" followed by a formatter name are treated as relative parameters. The first instance of a relative parameter interpolates the first positional argument, the second the second, etc.
SimpleCodeWriter = new SimpleCodeWriter();
writer.write("$L $L $L", "a", "b", "c");
System.out.println(writer.toString());
// Outputs: "a b c"
All relative arguments must be used as part of an expression and relative interpolation cannot be mixed with positional variables.
Placeholders in the form of "$" followed by a positive number, followed by a formatter name are treated as positional parameters. The number refers to the 1-based index of the argument to interpolate.
SimpleCodeWriter = new SimpleCodeWriter();
writer.write("$1L $2L $3L, $3L $2L $1L", "a", "b", "c");
System.out.println(writer.toString());
// Outputs: "a b c c b a"
All positional arguments must be used as part of an expression and relative interpolation cannot be mixed with positional variables.
Named parameters are parameters that take a value from the context of
the current state. They take the following form $<variable>:<formatter>
,
where <variable>
is a string that starts with a lowercase letter,
followed by any number of [A-Za-z0-9_#$.]
characters, and
<formatter>
is the name of a formatter.
SimpleCodeWriter = new SimpleCodeWriter();
writer.putContext("foo", "a");
writer.putContext("baz.bar", "b");
writer.write("$foo:L $baz.bar:L");
System.out.println(writer.toString());
// Outputs: "a b"
You can escape the "$" character using two "$$".
SimpleCodeWriter = new SimpleCodeWriter().write("$$L");
System.out.println(writer.toString());
// Outputs: "$L"
The character used to start a code block expression can be customized
to make it easier to write code that makes heavy use of $
. The
default character used to start an expression is, $
, but this can
be changed for the current state of the AbstractCodeWriter by calling
setExpressionStart(char)
. A custom start character can be escaped
using two start characters in a row. For example, given a custom start
character of #
, #
can be escaped using ##
.
SimpleCodeWriter = new SimpleCodeWriter();
writer.setExpressionStart('#');
writer.write("#L ##L $L", "hi");
System.out.println(writer.toString());
// Outputs: "hi #L $L"
The start character cannot be set to ' ' or '\n'.
AbstractCodeWriter
provides a short cut for opening code blocks that
have an opening an closing delimiter (for example, "{" and "}") and that
require indentation inside of the delimiters. Calling openBlock(java.lang.String, java.lang.Object...)
and providing the opening statement will write and format a line followed
by indenting one level. Calling closeBlock(java.lang.String, java.lang.Object...)
will first dedent and
then print a formatted statement.
SimpleCodeWriter = new SimpleCodeWriter()
.openBlock("if ($L) {", someValue)
.write("System.out.println($S);", "Hello!")
.closeBlock("}");
The above example outputs (assuming someValue is equal to "foo"):
if (foo) {
System.out.println("Hello!");
}
AbstractCodeWriter can maintain a stack of transformation states, including
the text used to indent, a prefix to add before each line, newline character,
the number of times to indent, a map of context values, whether or not
whitespace is trimmed from the end of newlines, whether or not the automatic
insertion of newlines is disabled, the character used to start code
expressions (defaults to $
), and formatters. State can be pushed onto
the stack using pushState()
which copies the current state. Mutations
can then be made to the top-most state of the AbstractCodeWriter and do not affect
previous states. The previous transformation state of the AbstractCodeWriter can later
be restored using popState()
.
AbstractCodeWriter is stateful, and a prefix can be added before each line. This is useful for doing things like create Javadoc strings:
SimpleCodeWriter = new SimpleCodeWriter();
writer
.pushState()
.write("/**")
.setNewlinePrefix(" * ")
.write("This is some docs.")
.write("And more docs.\n\n\n")
.write("Foo.")
.popState()
.write(" *\/");
The above example outputs:
/**
* This is some docs.
* And more docs.
*
* Foo.
*\/
^ Minus this escape character
AbstractCodeWriter maintains some global state that is not affected by
pushState()
and popState()
:
AbstractCodeWriter
to a string.Many coding standards recommend limiting the number of successive blank
lines. This can be handled automatically by AbstractCodeWriter
by calling
trimBlankLines
. The removal of blank lines is handled when the
AbstractCodeWriter
is converted to a string. Lines that consist solely
of spaces or tabs are considered blank. If the number of blank lines
exceeds the allowed threshold, they are omitted from the result.
Trailing spaces can be automatically trimmed from each line by calling
trimTrailingSpaces()
.
In the following example:
SimpleCodeWriter = new SimpleCodeWriter();
String result = writer.trimTrailingSpaces().write("hello ").toString();
The value of result
contains "hello"
AbstractCodeWriter
can be extended to add functionality for specific
programming languages. For example, Java specific code generator could
be implemented that makes it easier to write Javadocs.
class JavaCodeWriter extends AbstractCodeWriter<JavaCodeWriter> {
public JavaCodeWriter javadoc(Runnable runnable) {
pushState()
write("/**")
setNewlinePrefix(" * ")
runnable.run();
popState()
write(" *\/");
return this;
}
}
JavaCodeWriter writer = new JavaCodeWriter();
writer.javadoc(() -> {
writer.write("This is an example.");
});
Named sections can be marked in the code writer that can be intercepted
and modified by section interceptors. This gives the
AbstractCodeWriter
a lightweight extension system for augmenting generated
code.
A section of code can be captured using a block state or an inline
section. Section names must match the following regular expression:
^[a-z]+[a-zA-Z0-9_.#$]*$
.
A block section is created by passing a string to pushState()
.
This string gives the state a name and captures all of the output written
inside of this state to an internal buffer. This buffer is then passed to
each registered interceptor for that name. These interceptors can choose
to use the default contents of the section or emit entirely different
content. Interceptors are expected to make calls to the AbstractCodeWriter
in order to emit content. Interceptors need to have a reference to the
AbstractCodeWriter
as one is not provided to them when they are invoked.
Interceptors are invoked in the order in which they are added to the
CodeBuilder
.
SimpleCodeWriter = new SimpleCodeWriter();
writer.onSection("example", text -> writer.write("Intercepted: " + text));
writer.pushState("example");
writer.write("Original contents");
writer.popState();
System.out.println(writer.toString());
// Outputs: "Intercepted: Original contents\n"
CodeWriter
interpolation
format that appends "@" followed by the section name. Inline sections are
function just like block sections, but they can appear inline inside of
other content passed in calls to write(java.lang.Object, java.lang.Object...)
. An inline section
that makes no calls to write(java.lang.Object, java.lang.Object...)
expands to an empty string.
Inline sections are created in a format string inside of braced arguments
after the formatter. For example, ${L@foo}
is an inline section
that uses the literal "L" value of a relative argument as the default value
of the section and allows AbstractCodeWriter registered for the "foo" section to
make calls to the CodeWriter
to modify the section.
SimpleCodeWriter = new SimpleCodeWriter();
writer.onSection("example", text -> writer.write("Intercepted: " + text));
writer.write("Leading text...${L@example}...Trailing text...", "foo");
System.out.println(writer.toString());
// Outputs: "Leading text...Intercepted: foo...Trailing text...\n"
Inline sections are useful for composing sets or lists from any code with access to AbstractCodeWriter
:
SimpleCodeWriter = new SimpleCodeWriter();
writer.onSection("example", text -> writer.write(text + "1, "));
writer.onSection("example", text -> writer.write(text + "2, "));
writer.onSection("example", text -> writer.write(text + "3"));
writer.write("[${L@example}]", "");
System.out.println(writer.toString());
// Outputs: "[1, 2, 3]\n"
The long-form interpolation syntax allows for
inline block alignment, which means that any newline emitted by
the interpolation is automatically aligned with the column of where the
interpolation occurs. Inline block indentation is defined by preceding
the closing '}' character with '|' (e.g., ${L|}
):
SimpleCodeWriter = new SimpleCodeWriter();
writer.write("$L: ${L|}", "Names", "Bob\nKaren\nLuis");
System.out.println(writer.toString());
// Outputs: "Names: Bob\n Karen\n Luis\n"
Alignment occurs either statically or dynamically based on the characters that come before interpolation. If all of the characters in the literal template that come before interpolation are spaces and tabs, then those characters are used when indenting newlines. Otherwise, the number of characters written as the template result that come before interpolation are used when indenting (this takes into account any interpolation that may precede block interpolation).
Block interpolation is particularly used when using text blocks in Java because it allows templates to more closely match their end result.
// Assume handleNull, handleA, and handleB are Runnable.
writer.write("""
if (foo == null) {
${C|}
} else if (foo == "a") {
${C|}
} else if (foo == "b") {
${C|}
}
""",
handleNull,
handleA,
handleB);
AbstractCodeWriter is a lightweight template engine that supports conditional blocks and loops.
Conditional blocks are defined using the following syntax:
${?foo}
Foo is set: ${foo:L}
${/foo}
Assuming foo
is truthy and set to "hi", then the above template
outputs: "Foo is set: hi"
In the above example, "?" indicates that the expression is a conditional block
to check if the named parameter "foo" is truthy. If it is, then the contents of the
block up to the matching closing block, ${/foo}
, are evaluated. If the
condition is not satisfied, then contents of the block are skipped.
You can check if a named property is falsey using "^":
${^foo}
Foo is not set
${/foo}
Assuming foo
is set to "hi", then the above template outputs nothing.
If foo
is falsey, then the above template output "Foo is not set".
The following values are considered falsey:
String
Iterable
Map
Optional
Values that are not falsey are considered truthy.
Loops can be created to repeat a section of a template for each value stored in a list or each each key value pair stored in a map. Loops are created using "#".
The following template with a "foo" value of {"key1": "a", "key2": "b", "key3": "c"}:
${#foo}
- ${key:L}: ${value:L} (first: ${key.first:L}, last: ${key.last:L})
${/foo}
Evaluates to:
- key1: a (first: true, last: false)
- key2: b (first: false, last: false)
- key3: c (first: false, last: true)
Each iteration of the loop pushes a new state in the writer that sets the following context properties:
A custom variable name can be used in loops. For example:
${#foo as key1, value1}
- ${key1:L}: ${value1:L} (first: ${key1.first:L}, last: ${key1.last:L})
${/foo}
Conditional blocks that occur on lines that only contain whitespace are not written to the template output. For example, if the condition in the following template evaluates to falsey, then the template expands to an empty string:
${?foo}
Foo is set: ${foo:L}
${/foo}
Whitespace that comes before an expression can be removed by putting "~" at the beginning of an expression.
Assuming that the first positional argument is "hi":
Greeting:
${~L}
Expands to:
Greeting:hi
Whitespace that comes after an expression can be removed by adding "~" to the end of the expression:
${L~}
.
Expands to:
hi.
Leading whitespace cannot be removed when using inline block alignment ('|'). The following is invalid:
${~C|}
Constructor and Description |
---|
AbstractCodeWriter()
Creates a new SimpleCodeWriter that uses "\n" for a newline, four spaces
for indentation, does not strip trailing whitespace, does not flatten
multiple successive blank lines into a single blank line, and adds no
trailing new line.
|
Modifier and Type | Method and Description |
---|---|
T |
call(java.lang.Runnable task)
Allows calling out to arbitrary code for things like looping or
conditional writes without breaking method chaining.
|
T |
closeBlock(java.lang.String textAfterNewline,
java.lang.Object... args)
Closes a block of syntax by writing a newline, dedenting, then writing text.
|
java.util.function.Consumer<T> |
consumer(java.util.function.Consumer<T> consumer)
A simple helper method that makes it easier to invoke the built-in
C
(call) formatter using a Consumer where T is the specific type
of AbstractCodeWriter . |
void |
copySettingsFrom(AbstractCodeWriter<T> other)
Copies settings from the given AbstractCodeWriter into this AbstractCodeWriter.
|
T |
dedent()
Removes one level of indentation from all lines.
|
T |
dedent(int levels)
Removes a specific number of indentations from all lines.
|
T |
disableNewlines()
Disables the automatic appending of newlines in the current state.
|
T |
enableNewlines()
Enables the automatic appending of newlines in the current state.
|
T |
ensureNewline()
Ensures that the last text written to the writer was a newline as defined in
the current state and inserts one if necessary.
|
java.lang.String |
format(java.lang.Object content,
java.lang.Object... args)
Creates a formatted string using formatter expressions and variadic
arguments.
|
static java.lang.String |
formatLiteral(java.lang.Object value)
Provides the default functionality for formatting literal values.
|
java.lang.Object |
getContext(java.lang.String key)
Gets a named contextual key-value pair from the current state.
|
<C> C |
getContext(java.lang.String key,
java.lang.Class<C> type)
Gets a named context key-value pair from the current state and
casts the value to the given type.
|
CodeWriterDebugInfo |
getDebugInfo()
Gets debug information about the current state of the AbstractCodeWriter, including
the path to the current state as returned by
getStateDebugPath() ,
and up to the last two lines of text written to the AbstractCodeWriter. |
CodeWriterDebugInfo |
getDebugInfo(int numberOfContextLines)
Gets debug information about the current state of the AbstractCodeWriter.
|
char |
getExpressionStart()
Get the expression start character of the current state.
|
int |
getIndentLevel()
Gets the indentation level of the current state.
|
java.lang.String |
getIndentText()
Gets the text used for indentation (defaults to four spaces).
|
boolean |
getInsertTrailingNewline()
Checks if the AbstractCodeWriter inserts a trailing newline (if necessary) when
converted to a string.
|
java.lang.String |
getNewline()
Gets the character used to represent newlines in the current state.
|
java.lang.String |
getNewlinePrefix()
Gets the prefix to prepend to every line after a new line is added
(except for an inserted trailing newline).
|
int |
getTrimBlankLines()
Returns the number of allowed consecutive newlines that are not
trimmed by the AbstractCodeWriter when written to a string.
|
boolean |
getTrimTrailingSpaces()
Returns true if the trailing spaces in the current state are trimmed.
|
T |
indent()
Indents all text one level.
|
T |
indent(int levels)
Indents all text a specific number of levels.
|
T |
injectSection(CodeSection section)
Creates a section that contains no content used to allow
CodeInterceptor s
to inject content at specific locations. |
T |
insertTrailingNewline()
Configures the AbstractCodeWriter to always append a newline at the end of
the text if one is not already present.
|
T |
insertTrailingNewline(boolean trailingNewline)
Configures the AbstractCodeWriter to always append a newline at the end of
the text if one is not already present.
|
<S extends CodeSection> |
onSection(CodeInterceptor<S,T> interceptor)
Intercepts a section of code emitted for a strongly typed
CodeSection . |
T |
onSection(java.lang.String sectionName,
java.util.function.Consumer<java.lang.Object> interceptor)
Registers a function that intercepts the contents of a section and
writes to the
AbstractCodeWriter with the updated contents. |
T |
openBlock(java.lang.String textBeforeNewline,
java.lang.Object... args)
Opens a block of syntax by writing text, a newline, then indenting.
|
T |
openBlock(java.lang.String textBeforeNewline,
java.lang.String textAfterNewline,
java.lang.Object[] args,
java.lang.Runnable f)
Opens a block of syntax by writing
textBeforeNewline , a newline, then
indenting, then executes the given Runnable , then closes the block of
syntax by writing a newline, dedenting, then writing textAfterNewline . |
T |
openBlock(java.lang.String textBeforeNewline,
java.lang.String textAfterNewline,
java.lang.Object arg1,
java.lang.Object arg2,
java.lang.Object arg3,
java.lang.Object arg4,
java.lang.Object arg5,
java.lang.Runnable f)
Opens a block of syntax by writing
textBeforeNewline , a newline, then
indenting, then executes the given Runnable , then closes the block of
syntax by writing a newline, dedenting, then writing textAfterNewline . |
T |
openBlock(java.lang.String textBeforeNewline,
java.lang.String textAfterNewline,
java.lang.Object arg1,
java.lang.Object arg2,
java.lang.Object arg3,
java.lang.Object arg4,
java.lang.Runnable f)
Opens a block of syntax by writing
textBeforeNewline , a newline, then
indenting, then executes the given Runnable , then closes the block of
syntax by writing a newline, dedenting, then writing textAfterNewline . |
T |
openBlock(java.lang.String textBeforeNewline,
java.lang.String textAfterNewline,
java.lang.Object arg1,
java.lang.Object arg2,
java.lang.Object arg3,
java.lang.Runnable f)
Opens a block of syntax by writing
textBeforeNewline , a newline, then
indenting, then executes the given Runnable , then closes the block of
syntax by writing a newline, dedenting, then writing textAfterNewline . |
T |
openBlock(java.lang.String textBeforeNewline,
java.lang.String textAfterNewline,
java.lang.Object arg1,
java.lang.Object arg2,
java.lang.Runnable f)
Opens a block of syntax by writing
textBeforeNewline , a newline, then
indenting, then executes the given Runnable , then closes the block of
syntax by writing a newline, dedenting, then writing textAfterNewline . |
T |
openBlock(java.lang.String textBeforeNewline,
java.lang.String textAfterNewline,
java.lang.Object arg1,
java.lang.Runnable f)
Opens a block of syntax by writing
textBeforeNewline , a newline, then
indenting, then executes the given Runnable , then closes the block of
syntax by writing a newline, dedenting, then writing textAfterNewline . |
T |
openBlock(java.lang.String textBeforeNewline,
java.lang.String textAfterNewline,
java.lang.Runnable f)
Opens a block of syntax by writing
textBeforeNewline , a newline, then
indenting, then executes the given Runnable , then closes the block of
syntax by writing a newline, dedenting, then writing textAfterNewline . |
T |
popState()
Pops the current AbstractCodeWriter state from the state stack.
|
T |
pushFilteredState(java.util.function.Function<java.lang.String,java.lang.String> filter)
Pushes an anonymous named state that is always passed through the given
filter function before being written to the writer.
|
T |
pushState()
Copies and pushes the current state to the state stack.
|
T |
pushState(CodeSection section)
Pushes a strongly typed section extension point.
|
T |
pushState(java.lang.String sectionName)
Copies and pushes the current state to the state stack using a named
state that can be intercepted by functions registered with
onSection(CodeInterceptor) . |
T |
putContext(java.util.Map<java.lang.String,java.lang.Object> mappings)
Adds a map of named key-value pair to the context of the current state.
|
T |
putContext(java.lang.String key,
java.lang.Object value)
Adds a named key-value pair to the context of the current state.
|
T |
putFormatter(char identifier,
java.util.function.BiFunction<java.lang.Object,java.lang.String,java.lang.String> formatFunction)
Adds a custom formatter expression to the current state of the
AbstractCodeWriter . |
T |
removeContext(java.lang.String key)
Removes a named key-value pair from the context of the current state.
|
T |
setExpressionStart(char expressionStart)
Sets the character used to start expressions in the current state when calling
write(java.lang.Object, java.lang.Object...) , writeInline(java.lang.Object, java.lang.Object...) , openBlock(java.lang.String, java.lang.Object...) , etc. |
T |
setIndentText(java.lang.String indentText)
Sets the text used for indentation (defaults to four spaces).
|
T |
setNewline(char newline)
Sets the character used to represent newlines in the current state
("\n" is the default).
|
T |
setNewline(java.lang.String newline)
Sets the character used to represent newlines in the current state
("\n" is the default).
|
T |
setNewlinePrefix(java.lang.String newlinePrefix)
Sets a prefix to prepend to every line after a new line is added
(except for an inserted trailing newline).
|
java.lang.String |
toString()
Gets the contents of the generated code.
|
T |
trimBlankLines()
Ensures that no more than one blank line occurs in succession.
|
T |
trimBlankLines(int trimBlankLines)
Ensures that no more than the given number of newlines can occur
in succession, removing consecutive newlines that exceed the given
threshold.
|
T |
trimTrailingSpaces()
Enables the trimming of trailing spaces on a line.
|
T |
trimTrailingSpaces(boolean trimTrailingSpaces)
Configures if trailing spaces on a line are removed.
|
T |
unwrite(java.lang.Object content,
java.lang.Object... args)
Remove the most recent text written to the AbstractCodeWriter if and only
if the last written text is exactly equal to the given expanded
content string.
|
T |
write(java.lang.Object content,
java.lang.Object... args)
Writes text to the AbstractCodeWriter and appends a newline.
|
T |
writeInline(java.lang.Object content,
java.lang.Object... args)
Writes text to the AbstractCodeWriter without appending a newline.
|
T |
writeInlineWithNoFormatting(java.lang.Object content)
Writes inline text to the AbstractCodeWriter with no formatting.
|
T |
writeOptional(java.lang.Object content)
Optionally writes text to the AbstractCodeWriter and appends a newline
if a value is present.
|
T |
writeWithNoFormatting(java.lang.Object content)
Writes text to the AbstractCodeWriter and appends a newline.
|
public AbstractCodeWriter()
public void copySettingsFrom(AbstractCodeWriter<T> other)
The settings of the other
AbstractCodeWriter will overwrite
both global and state-based settings of this AbstractCodeWriter. Formatters of
the other
AbstractCodeWriter will be merged with the formatters of this
AbstractCodeWriter, and in the case of conflicts, the formatters of the
other
will take precedence.
Stateful settings of the other
AbstractCodeWriter are copied into
the current state of this AbstractCodeWriter. Only the settings of
the top-most state is copied. Other states, and the contents of the
top-most state are not copied.
SimpleCodeWritera = new SimpleCodeWriter();
a.setExpressionStart('#');
SimpleCodeWriterb = new SimpleCodeWriter();
b.copySettingsFrom(a);
assert(b.getExpressionStart() == '#');
other
- CodeWriter to copy settings from.public static java.lang.String formatLiteral(java.lang.Object value)
This formatter is registered by default as the literal "L" formatter, and is called in the default string "S" formatter before escaping any characters in the string.
null
: Formatted as an empty string.Optional
: Formatted as an empty string.Optional
with value: Formatted as the formatted value in the optional.String.valueOf(java.lang.Object)
.value
- Value to format.public T putFormatter(char identifier, java.util.function.BiFunction<java.lang.Object,java.lang.String,java.lang.String> formatFunction)
AbstractCodeWriter
.
The provided identifier
string must match the following ABNF:
%x21-23 ; ( '!' - '#' ) / %x25-2F ; ( '%' - '/' ) / %x3A-60 ; ( ':' - '`' ) / %x7B-7E ; ( '{' - '~' )
identifier
- Formatter identifier to associate with this formatter.formatFunction
- Formatter function that formats the given object as a String.
The formatter is give the value to format as an object
(use .toString to access the string contents) and the
current indentation string of the AbstractCodeWriter.public T setExpressionStart(char expressionStart)
write(java.lang.Object, java.lang.Object...)
, writeInline(java.lang.Object, java.lang.Object...)
, openBlock(java.lang.String, java.lang.Object...)
, etc.
By default, $
is used to start expressions (for example
$L
. However, some programming languages frequently give
syntactic meaning to $
, making this an inconvenient syntactic
character for the AbstractCodeWriter. In these cases, the character used to
start a AbstractCodeWriter expression can be changed. Just like $
, the
custom start character can be escaped using two subsequent start
characters (e.g., $$
).
expressionStart
- Character to use to start expressions.public char getExpressionStart()
This value should not be cached and reused across pushed and popped
states. This value is "$" by default, but it can be changed using
setExpressionStart(char)
.
public java.lang.String toString()
The result will have an appended newline if the AbstractCodeWriter is configured to always append a newline. A newline is only appended in these cases if the result does not already end with a newline.
toString
in class java.lang.Object
public T pushState()
This method is used to prepare for a corresponding popState()
operation later. It stores the current state of the AbstractCodeWriter into a
stack and keeps it active. After pushing, mutations can be made to the
state of the AbstractCodeWriter without affecting the previous state on the
stack. Changes to the state of the AbstractCodeWriter can be undone by using
popState()
, which Returns self state to the state
it was in before calling pushState
.
public T pushState(java.lang.String sectionName)
onSection(CodeInterceptor)
.
The text written while in this state is buffered and passed to each
state interceptor. If no text is written by the section or an
interceptor, nothing is changed on the AbstractCodeWriter
. This
behavior allows for placeholder sections to be added into
AbstractCodeWriter
generators in order to provide extension points
that can be otherwise empty.
sectionName
- Name of the section to set on the state.public T pushState(CodeSection section)
Interceptors can be registered to intercept this specific type
of CodeSection using a CodeInterceptor
and providing a
class for which section
is an instance.
section
- The section value to push.onSection(CodeInterceptor)
public T injectSection(CodeSection section)
CodeInterceptor
s
to inject content at specific locations.section
- The code section to register that can be intercepted by type.public final CodeWriterDebugInfo getDebugInfo()
getStateDebugPath()
,
and up to the last two lines of text written to the AbstractCodeWriter.
This debug information is used in most exceptions thrown by AbstractCodeWriter to provide additional context when something goes wrong. It can also be used by subclasses and collaborators to aid in debugging codegen issues.
getDebugInfo(int)
public CodeWriterDebugInfo getDebugInfo(int numberOfContextLines)
This method can be overridden in order to add more metadata to the created debug info object.
numberOfContextLines
- Include the last N lines in the output. Set to 0 to omit lines.getDebugInfo()
public T pushFilteredState(java.util.function.Function<java.lang.String,java.lang.String> filter)
filter
- Function that maps over the entire section when popped.public T popState()
This method is used to reverse a previous pushState()
operation. It configures the current AbstractCodeWriter state to what it was
before the last preceding pushState
call.
java.lang.IllegalStateException
- if there a no states to pop.public T onSection(java.lang.String sectionName, java.util.function.Consumer<java.lang.Object> interceptor)
AbstractCodeWriter
with the updated contents.
The interceptor
function is expected to have a reference to
the AbstractCodeWriter
and to mutate it when they are invoked. Each
interceptor is invoked in their own isolated pushed/popped states.
The text provided to interceptor
does not contain a trailing
new line. A trailing new line is expected to be injected automatically
when the results of intercepting the contents are written to the
AbstractCodeWriter
. A result is only written if the interceptors write
a non-null, non-empty string, allowing for empty placeholders to be
added that don't affect the resulting layout of the code.
SimpleCodeWriter = new SimpleCodeWriter();
// Prepend text to a section named "foo".
writer.onSectionPrepend("foo", () -> writer.write("A"));
// Write text to a section, and ensure that the original
// text is written too.
writer.onSection("foo", text -> {
// Write before the original text.
writer.write("A");
// Write the original text of the section.
writer.writeWithNoFormatting(text);
// Write more text to the section.
writer.write("C");
});
// Create the section, write to it, then close the section.
writer.pushState("foo").write("B").popState();
assert(writer.toString().equals("A\nB\nC\n"));
This method is a wrapper around onSection(CodeInterceptor)
that has several limitations:
interceptor
is expected to have a reference
to an AbstractCodeWriter
so that write calls can be made.onSection(CodeInterceptor)
must be used directly and
careful use of writeInlineWithNoFormatting(Object)
is
required when writing the previous contents to the interceptor.CodeInterceptor
s do.
The newline handling functionality provided by this method can be
reproduced using a CodeInterceptor
by removing trailing newlines
using removeTrailingNewline(String)
.
SimpleCodeWriter = new SimpleCodeWriter();
CodeInterceptor<CodeSection, SimpleCodeWriter> interceptor = CodeInterceptor.forName(sectionName, (w, p) -> {
String trimmedContent = removeTrailingNewline(p);
interceptor.accept(trimmedContent);
})
writer.onSection(interceptor);
sectionName
- The name of the section to intercept.interceptor
- The function to intercept with.public <S extends CodeSection> T onSection(CodeInterceptor<S,T> interceptor)
CodeSection
.
These section interceptors provide a kind of event-based hook system for
AbstractCodeWriters that add extension points when generating code. The function has
the ability to completely ignore the original contents of the section, to
prepend text to it, and append text to it. Intercepting functions are
expected to have a reference to the AbstractCodeWriter
and to mutate it
when they are invoked. Each interceptor is invoked in their own
isolated pushed/popped states.
Interceptors are registered on the current state of the
AbstractCodeWriter
. When the state to which an interceptor is registered
is popped, the interceptor is no longer in scope.
S
- The type of section being intercepted.interceptor
- A consumer that takes the writer and strongly typed section.public T disableNewlines()
Methods like write(java.lang.Object, java.lang.Object...)
, openBlock(java.lang.String, java.lang.Object...)
, and closeBlock(java.lang.String, java.lang.Object...)
will not automatically append newlines when a state has this flag set.
public T enableNewlines()
public T setNewline(java.lang.String newline)
When the provided string is empty (""), then newlines are disabled
in the current state. This is exactly equivalent to calling
disableNewlines()
, and does not actually change the newline
character of the current state.
Setting the newline character to a non-empty string implicitly enables newlines in the current state.
newline
- Newline character to use.public T setNewline(char newline)
This call also enables newlines in the current state by calling
enableNewlines()
.
newline
- Newline character to use.public java.lang.String getNewline()
public T setIndentText(java.lang.String indentText)
indentText
- Indentation text.public final java.lang.String getIndentText()
public T trimTrailingSpaces()
public T trimTrailingSpaces(boolean trimTrailingSpaces)
trimTrailingSpaces
- Set to true to trim trailing spaces.public boolean getTrimTrailingSpaces()
public T trimBlankLines()
public T trimBlankLines(int trimBlankLines)
trimBlankLines
- Number of allowed consecutive newlines. Set to
-1 to perform no trimming. Set to 0 to allow no blank lines. Set to
1 or more to allow for no more than N consecutive blank lines.public int getTrimBlankLines()
public T insertTrailingNewline()
This setting is not captured as part of push/popState.
public T insertTrailingNewline(boolean trailingNewline)
This setting is not captured as part of push/popState.
trailingNewline
- True if a newline is added.public boolean getInsertTrailingNewline()
public T setNewlinePrefix(java.lang.String newlinePrefix)
newlinePrefix
- Newline prefix to use.public java.lang.String getNewlinePrefix()
public T indent()
public T indent(int levels)
levels
- Number of levels to indent.public int getIndentLevel()
public T dedent()
public T dedent(int levels)
Set to -1 to dedent back to 0 (root).
levels
- Number of levels to remove.java.lang.IllegalStateException
- when trying to dedent too far.public T openBlock(java.lang.String textBeforeNewline, java.lang.Object... args)
String result = new SimpleCodeWriter()
.openBlock("public final class $L {", "Foo")
.openBlock("public void main(String[] args) {")
.write("System.out.println(args[0]);")
.closeBlock("}")
.closeBlock("}")
.toString();
textBeforeNewline
- Text to write before writing a newline and indenting.args
- String arguments to use for formatting.public T openBlock(java.lang.String textBeforeNewline, java.lang.String textAfterNewline, java.lang.Runnable f)
textBeforeNewline
, a newline, then
indenting, then executes the given Runnable
, then closes the block of
syntax by writing a newline, dedenting, then writing textAfterNewline
.
SimpleCodeWriter = new SimpleCodeWriter();
writer.openBlock("public final class $L {", "}", "Foo", () -> {
writer.openBlock("public void main(String[] args) {", "}", () -> {
writer.write("System.out.println(args[0]);");
})
});
textBeforeNewline
- Text to write before writing a newline and indenting.textAfterNewline
- Text to write after writing a newline and indenting.f
- Runnable function to execute inside of the block.public T openBlock(java.lang.String textBeforeNewline, java.lang.String textAfterNewline, java.lang.Object arg1, java.lang.Runnable f)
textBeforeNewline
, a newline, then
indenting, then executes the given Runnable
, then closes the block of
syntax by writing a newline, dedenting, then writing textAfterNewline
.textBeforeNewline
- Text to write before writing a newline and indenting.textAfterNewline
- Text to write after writing a newline and indenting.arg1
- First positional argument to substitute into textBeforeNewline
.f
- Runnable function to execute inside of the block.public T openBlock(java.lang.String textBeforeNewline, java.lang.String textAfterNewline, java.lang.Object arg1, java.lang.Object arg2, java.lang.Runnable f)
textBeforeNewline
, a newline, then
indenting, then executes the given Runnable
, then closes the block of
syntax by writing a newline, dedenting, then writing textAfterNewline
.textBeforeNewline
- Text to write before writing a newline and indenting.textAfterNewline
- Text to write after writing a newline and indenting.arg1
- First positional argument to substitute into textBeforeNewline
.arg2
- Second positional argument to substitute into textBeforeNewline
.f
- Runnable function to execute inside of the block.public T openBlock(java.lang.String textBeforeNewline, java.lang.String textAfterNewline, java.lang.Object arg1, java.lang.Object arg2, java.lang.Object arg3, java.lang.Runnable f)
textBeforeNewline
, a newline, then
indenting, then executes the given Runnable
, then closes the block of
syntax by writing a newline, dedenting, then writing textAfterNewline
.textBeforeNewline
- Text to write before writing a newline and indenting.textAfterNewline
- Text to write after writing a newline and indenting.arg1
- First positional argument to substitute into textBeforeNewline
.arg2
- Second positional argument to substitute into textBeforeNewline
.arg3
- Third positional argument to substitute into textBeforeNewline
.f
- Runnable function to execute inside of the block.public T openBlock(java.lang.String textBeforeNewline, java.lang.String textAfterNewline, java.lang.Object arg1, java.lang.Object arg2, java.lang.Object arg3, java.lang.Object arg4, java.lang.Runnable f)
textBeforeNewline
, a newline, then
indenting, then executes the given Runnable
, then closes the block of
syntax by writing a newline, dedenting, then writing textAfterNewline
.textBeforeNewline
- Text to write before writing a newline and indenting.textAfterNewline
- Text to write after writing a newline and indenting.arg1
- First positional argument to substitute into textBeforeNewline
.arg2
- Second positional argument to substitute into textBeforeNewline
.arg3
- Third positional argument to substitute into textBeforeNewline
.arg4
- Fourth positional argument to substitute into textBeforeNewline
.f
- Runnable function to execute inside of the block.public T openBlock(java.lang.String textBeforeNewline, java.lang.String textAfterNewline, java.lang.Object arg1, java.lang.Object arg2, java.lang.Object arg3, java.lang.Object arg4, java.lang.Object arg5, java.lang.Runnable f)
textBeforeNewline
, a newline, then
indenting, then executes the given Runnable
, then closes the block of
syntax by writing a newline, dedenting, then writing textAfterNewline
.textBeforeNewline
- Text to write before writing a newline and indenting.textAfterNewline
- Text to write after writing a newline and indenting.arg1
- First positional argument to substitute into textBeforeNewline
.arg2
- Second positional argument to substitute into textBeforeNewline
.arg3
- Third positional argument to substitute into textBeforeNewline
.arg4
- Fourth positional argument to substitute into textBeforeNewline
.arg5
- Fifth positional argument to substitute into textBeforeNewline
.f
- Runnable function to execute inside of the block.public T openBlock(java.lang.String textBeforeNewline, java.lang.String textAfterNewline, java.lang.Object[] args, java.lang.Runnable f)
textBeforeNewline
, a newline, then
indenting, then executes the given Runnable
, then closes the block of
syntax by writing a newline, dedenting, then writing textAfterNewline
.textBeforeNewline
- Text to write before writing a newline and indenting.textAfterNewline
- Text to write after writing a newline and indenting.args
- Arguments to substitute into textBeforeNewline
.f
- Runnable function to execute inside of the block.public T closeBlock(java.lang.String textAfterNewline, java.lang.Object... args)
textAfterNewline
- Text to write after writing a newline and dedenting.args
- String arguments to use for formatting.public T writeWithNoFormatting(java.lang.Object content)
The provided text does not use any kind of expression formatting.
Indentation and the newline prefix is only prepended if the writer's cursor is at the beginning of a newline.
content
- Content to write.public final T writeInlineWithNoFormatting(java.lang.Object content)
The provided text does not use any kind of expression formatting. Indentation and the newline prefix is only prepended if the writer's cursor is at the beginning of a newline.
content
- Inline content to write.public final java.lang.String format(java.lang.Object content, java.lang.Object... args)
Important: if the formatters that are executed while formatting the
given content
string mutate the AbstractCodeWriter, it could leave the
SimpleCodeWriterin an inconsistent state. For example, some AbstractCodeWriter
implementations manage imports and dependencies automatically based on
code that is referenced by formatters. If such an expression is used
with this format method but the returned String is never written to the
AbstractCodeWriter, then the AbstractCodeWriter might be mutated to track dependencies
that aren't actually necessary.
SimpleCodeWriter = new SimpleCodeWriter();
String name = "Person";
String formatted = writer.format("Hello, $L", name);
assert(formatted.equals("Hello, Person"));
content
- Content to format.args
- String arguments to use for formatting.write(java.lang.Object, java.lang.Object...)
,
putFormatter(char, java.util.function.BiFunction<java.lang.Object, java.lang.String, java.lang.String>)
public java.util.function.Consumer<T> consumer(java.util.function.Consumer<T> consumer)
C
(call) formatter using a Consumer
where T
is the specific type
of AbstractCodeWriter
.
Instead of having to type this:
writer.write("$C", (Consumer<MyWriter>) (w) -> w.write("Hi"));
You can write:
writer.write("$C", writer.consumer(w -> w.write("Hi"));
consumer
- The consumer to call.public T call(java.lang.Runnable task)
task
- Method to invoke.public T write(java.lang.Object content, java.lang.Object... args)
The provided text is automatically formatted using variadic arguments.
Indentation and the newline prefix is only prepended if the writer's cursor is at the beginning of a newline.
content
- Content to write.args
- String arguments to use for formatting.public T writeInline(java.lang.Object content, java.lang.Object... args)
The provided text is automatically formatted using variadic arguments.
Indentation and the newline prefix is only prepended if the writer's cursor is at the beginning of a newline.
If newlines are present in the given string, each of those lines will receive proper indentation.
content
- Content to write.args
- String arguments to use for formatting.public T ensureNewline()
public T writeOptional(java.lang.Object content)
If the provided content
value is null
, nothing is
written. If the provided content
value is an empty
Optional
, nothing is written. If the result of calling
toString
on content
results in an empty string,
nothing is written. Finally, if the value is a non-empty string,
the content is written to the AbstractCodeWriter
at the current
level of indentation, and a newline is appended.
content
- Content to write if present.public T unwrite(java.lang.Object content, java.lang.Object... args)
This can be useful, for example, for use cases like removing trailing commas from lists of values.
For example, the following will remove ", there." from the end of the AbstractCodeWriter:
SimpleCodeWriter = new SimpleCodeWriter();
writer.writeInline("Hello, there.");
writer.unwrite(", there.");
assert(writer.toString().equals("Hello\n"));
However, the following call to unwrite will do nothing because the last text written to the AbstractCodeWriter does not match:
SimpleCodeWriter = new SimpleCodeWriter();
writer.writeInline("Hello.");
writer.unwrite("there.");
assert(writer.toString().equals("Hello.\n"));
content
- Content to write.args
- String arguments to use for formatting.public T putContext(java.lang.String key, java.lang.Object value)
These context values can be referenced by named interpolated parameters.
key
- Key to add to the context.value
- Value to associate with the key.public T putContext(java.util.Map<java.lang.String,java.lang.Object> mappings)
These context values can be referenced by named interpolated parameters.
mappings
- Key value pairs to add.public T removeContext(java.lang.String key)
key
- Key to add to remove from the current context.public java.lang.Object getContext(java.lang.String key)
key
- Key to retrieve.public <C> C getContext(java.lang.String key, java.lang.Class<C> type)
key
- Key to retrieve.type
- The type of value expected.java.lang.ClassCastException
- if the stored value is not null and does not match type
.