Printer final

final class Printer

Renders a Json value to a formatted String.

All whitespace is controlled through the spacing fields. Pre-built instances cover the most common cases:

• Printer.noSpaces — compact, no whitespace
• Printer.spaces2 / Printer.spaces4 — 2- or 4-space indentation
• Printer.indented — custom indentation string

Use copy to create variants and print to render.

Constructors

Printer()

Printer({
  String indent = '',
  String lbraceLeft = '',
  String lbraceRight = '',
  String rbraceLeft = '',
  String rbraceRight = '',
  String lbracketLeft = '',
  String lbracketRight = '',
  String rbracketLeft = '',
  String rbracketRight = '',
  String lrbracketsEmpty = '',
  String arrayCommaLeft = '',
  String arrayCommaRight = '',
  String objectCommaLeft = '',
  String objectCommaRight = '',
  String colonLeft = '',
  String colonRight = '',
  bool dropNullValues = false,
  bool escapeNonAscii = false,
})

Implementation

Printer({
  this.indent = '',
  this.lbraceLeft = '',
  this.lbraceRight = '',
  this.rbraceLeft = '',
  this.rbraceRight = '',
  this.lbracketLeft = '',
  this.lbracketRight = '',
  this.rbracketLeft = '',
  this.rbracketRight = '',
  this.lrbracketsEmpty = '',
  this.arrayCommaLeft = '',
  this.arrayCommaRight = '',
  this.objectCommaLeft = '',
  this.objectCommaRight = '',
  this.colonLeft = '',
  this.colonRight = '',
  this.dropNullValues = false,
  this.escapeNonAscii = false,
});

Properties

arrayCommaLeft final

final String arrayCommaLeft

Whitespace written before each array ,.

Implementation

final String arrayCommaLeft;

arrayCommaRight final

final String arrayCommaRight

Whitespace written after each array ,.

Implementation

final String arrayCommaRight;

colonLeft final

final String colonLeft

Whitespace written before each :.

Implementation

final String colonLeft;

colonRight final

final String colonRight

Whitespace written after each :.

Implementation

final String colonRight;

dropNullValues final

final bool dropNullValues

When true, fields whose value is JNull are omitted from objects.

Implementation

final bool dropNullValues;

escapeNonAscii final

final bool escapeNonAscii

When true, non-ASCII characters are escaped as \uXXXX sequences.

Implementation

final bool escapeNonAscii;

hashCode no setter inherited

int get hashCode

The hash code for this object.

A hash code is a single integer which represents the state of the object that affects operator == comparisons.

All objects have hash codes. The default hash code implemented by Object represents only the identity of the object, the same way as the default operator == implementation only considers objects equal if they are identical (see identityHashCode).

If operator == is overridden to use the object state instead, the hash code must also be changed to represent that state, otherwise the object cannot be used in hash based data structures like the default Set and Map implementations.

Hash codes must be the same for objects that are equal to each other according to operator ==. The hash code of an object should only change if the object changes in a way that affects equality. There are no further requirements for the hash codes. They need not be consistent between executions of the same program and there are no distribution guarantees.

Objects that are not equal are allowed to have the same hash code. It is even technically allowed that all instances have the same hash code, but if clashes happen too often, it may reduce the efficiency of hash-based data structures like HashSet or HashMap.

If a subclass overrides hashCode, it should override the operator == operator as well to maintain consistency.

Inherited from Object.

Implementation

external int get hashCode;

indent final

final String indent

The indentation string repeated per nesting level (e.g. ' ').

Implementation

final String indent;

lbraceLeft final

final String lbraceLeft

Whitespace written before the opening {.

Implementation

final String lbraceLeft;

lbraceRight final

final String lbraceRight

Whitespace written after the opening {.

Implementation

final String lbraceRight;

lbracketLeft final

final String lbracketLeft

Whitespace written before the opening [.

Implementation

final String lbracketLeft;

lbracketRight final

final String lbracketRight

Whitespace written after the opening [.

Implementation

final String lbracketRight;

lrbracketsEmpty final

final String lrbracketsEmpty

Whitespace between [ and ] for empty arrays.

Implementation

final String lrbracketsEmpty;

objectCommaLeft final

final String objectCommaLeft

Whitespace written before each object ,.

Implementation

final String objectCommaLeft;

objectCommaRight final

final String objectCommaRight

Whitespace written after each object ,.

Implementation

final String objectCommaRight;

rbraceLeft final

final String rbraceLeft

Whitespace written before the closing }.

Implementation

final String rbraceLeft;

rbraceRight final

final String rbraceRight

Whitespace written after the closing }.

Implementation

final String rbraceRight;

rbracketLeft final

final String rbracketLeft

Whitespace written before the closing ].

Implementation

final String rbracketLeft;

rbracketRight final

final String rbracketRight

Whitespace written after the closing ].

Implementation

final String rbracketRight;

runtimeType no setter inherited

Type get runtimeType

A representation of the runtime type of the object.

Inherited from Object.

Implementation

external Type get runtimeType;

Methods

copy()

Printer copy({
  String? indent,
  String? lbraceLeft,
  String? lbraceRight,
  String? rbraceLeft,
  String? rbraceRight,
  String? lbracketLeft,
  String? lbracketRight,
  String? rbracketLeft,
  String? rbracketRight,
  String? lrbracketsEmpty,
  String? arrayCommaLeft,
  String? arrayCommaRight,
  String? objectCommaLeft,
  String? objectCommaRight,
  String? colonLeft,
  String? colonRight,
  bool? dropNullValues,
  bool? escapeNonAscii,
})

Returns a copy of this printer with the given fields overridden.

Implementation

Printer copy({
  String? indent,
  String? lbraceLeft,
  String? lbraceRight,
  String? rbraceLeft,
  String? rbraceRight,
  String? lbracketLeft,
  String? lbracketRight,
  String? rbracketLeft,
  String? rbracketRight,
  String? lrbracketsEmpty,
  String? arrayCommaLeft,
  String? arrayCommaRight,
  String? objectCommaLeft,
  String? objectCommaRight,
  String? colonLeft,
  String? colonRight,
  bool? dropNullValues,
  bool? escapeNonAscii,
}) => Printer(
  indent: indent ?? this.indent,
  lbraceLeft: lbraceLeft ?? this.lbraceLeft,
  lbraceRight: lbraceRight ?? this.lbraceRight,
  rbraceLeft: rbraceLeft ?? this.rbraceLeft,
  rbraceRight: rbraceRight ?? this.rbraceRight,
  lbracketLeft: lbracketLeft ?? this.lbracketLeft,
  lbracketRight: lbracketRight ?? this.lbracketRight,
  rbracketLeft: rbracketLeft ?? this.rbracketLeft,
  rbracketRight: rbracketRight ?? this.rbracketRight,
  lrbracketsEmpty: lrbracketsEmpty ?? this.lrbracketsEmpty,
  arrayCommaLeft: arrayCommaLeft ?? this.arrayCommaLeft,
  arrayCommaRight: arrayCommaRight ?? this.arrayCommaRight,
  objectCommaLeft: objectCommaLeft ?? this.objectCommaLeft,
  objectCommaRight: objectCommaRight ?? this.objectCommaRight,
  colonLeft: colonLeft ?? this.colonLeft,
  colonRight: colonRight ?? this.colonRight,
  dropNullValues: dropNullValues ?? this.dropNullValues,
  escapeNonAscii: escapeNonAscii ?? this.escapeNonAscii,
);

noSuchMethod() inherited

dynamic noSuchMethod(Invocation invocation)

Invoked when a nonexistent method or property is accessed.

A dynamic member invocation can attempt to call a member which doesn't exist on the receiving object. Example:

dynamic object = 1;
object.add(42); // Statically allowed, run-time error

This invalid code will invoke the noSuchMethod method of the integer 1 with an Invocation representing the .add(42) call and arguments (which then throws).

Classes can override noSuchMethod to provide custom behavior for such invalid dynamic invocations.

A class with a non-default noSuchMethod invocation can also omit implementations for members of its interface. Example:

class MockList<T> implements List<T> {
  noSuchMethod(Invocation invocation) {
    log(invocation);
    super.noSuchMethod(invocation); // Will throw.
  }
}
void main() {
  MockList().add(42);
}

This code has no compile-time warnings or errors even though the MockList class has no concrete implementation of any of the List interface methods. Calls to List methods are forwarded to noSuchMethod, so this code will log an invocation similar to Invocation.method(#add, [42]) and then throw.

If a value is returned from noSuchMethod, it becomes the result of the original invocation. If the value is not of a type that can be returned by the original invocation, a type error occurs at the invocation.

The default behavior is to throw a NoSuchMethodError.

Inherited from Object.

Implementation

@pragma("vm:entry-point")
@pragma("wasm:entry-point")
external dynamic noSuchMethod(Invocation invocation);

print()

String print(Json json)

Renders json to a String according to this printer's configuration.

Implementation

String print(Json json) {
  final folder = _PrintFolder(this);
  json.foldWith(folder);
  return folder.buffer.toString();
}

toString() inherited

String toString()

A string representation of this object.

Some classes have a default textual representation, often paired with a static parse function (like int.parse). These classes will provide the textual representation as their string representation.

Other classes have no meaningful textual representation that a program will care about. Such classes will typically override toString to provide useful information when inspecting the object, mainly for debugging or logging.

Inherited from Object.

Implementation

external String toString();

Operators

operator ==() inherited

bool operator ==(Object other)

The equality operator.

The default behavior for all Objects is to return true if and only if this object and other are the same object.

Override this method to specify a different equality relation on a class. The overriding method must still be an equivalence relation. That is, it must be:

• Total: It must return a boolean for all arguments. It should never throw.

• Reflexive: For all objects o, o == o must be true.

• Symmetric: For all objects o1 and o2, o1 == o2 and o2 == o1 must either both be true, or both be false.

• Transitive: For all objects o1, o2, and o3, if o1 == o2 and o2 == o3 are true, then o1 == o3 must be true.

The method should also be consistent over time, so whether two objects are equal should only change if at least one of the objects was modified.

If a subclass overrides the equality operator, it should override the hashCode method as well to maintain consistency.

Inherited from Object.

Implementation

external bool operator ==(Object other);

Static Properties

noSpaces read / write

Printer noSpaces

getter:

Compact printer with no whitespace.

setter:

Compact printer with no whitespace.

Implementation

static Printer noSpaces = Printer();

spaces2 read / write

Printer spaces2

getter:

Indented printer using 2-space indentation.

setter:

Indented printer using 2-space indentation.

Implementation

static Printer spaces2 = indented('  ');

spaces4 read / write

Printer spaces4

getter:

Indented printer using 4-space indentation.

setter:

Indented printer using 4-space indentation.

Implementation

static Printer spaces4 = indented('    ');

Static Methods

indented()

Printer indented(String indent)

Creates an indented printer using indent as the per-level indentation string.

Implementation

static Printer indented(String indent) => Printer(
  indent: indent,
  lbraceRight: '\n',
  rbraceLeft: '\n',
  lbracketRight: '\n',
  rbracketLeft: '\n',
  lrbracketsEmpty: '\n',
  arrayCommaRight: '\n',
  objectCommaRight: '\n',
  colonLeft: ' ',
  colonRight: ' ',
);