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Add getters and ability to copy settings between CodeWriters #1067

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Feb 2, 2022
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Add getters and ability to copy settings between CodeWriters #1067

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40 changes: 36 additions & 4 deletions smithy-utils/src/main/java/software/amazon/smithy/utils/CodeFormatter.java
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Original file line number Diff line number Diff line change
Expand Up @@ -32,13 +32,43 @@ final class CodeFormatter {
'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '[', ']', '^', '_', '`', '{', '|', '}', '~');

private final Map<Character, BiFunction<Object, String, String>> formatters = new HashMap<>();
private final CodeFormatter parentFormatter;

void putFormatter(Character identifier, BiFunction<Object, String, String> formatter) {
CodeFormatter() {
this(null);
}

/**
* Create a CodeFormatter that also uses formatters of a parent CodeFormatter.
*
* @param parentFormatter Optional parent CodeFormatter to query when expanding formatters.
*/
CodeFormatter(CodeFormatter parentFormatter) {
this.parentFormatter = parentFormatter;
}

void putFormatter(Character identifier, BiFunction<Object, String, String> formatFunction) {
if (!VALID_FORMATTER_CHARS.contains(identifier)) {
throw new IllegalArgumentException("Invalid formatter identifier: " + identifier);
}

formatters.put(identifier, formatter);
formatters.put(identifier, formatFunction);
}

/**
* Gets a formatter function for a specific character.
*
* @param identifier Formatter identifier.
* @return Returns the found formatter, or null.
*/
BiFunction<Object, String, String> getFormatter(char identifier) {
BiFunction<Object, String, String> result = formatters.get(identifier);

if (result == null && parentFormatter != null) {
result = parentFormatter.getFormatter(identifier);
}

return result;
}

String format(char expressionStart, Object content, String indent, CodeWriter writer, Object... args) {
Expand Down Expand Up @@ -211,12 +241,14 @@ private Object getPositionalArgument(String content, int index, Object[] args) {
}

private String applyFormatter(State state, char formatter, Object argument, int startingBraceColumn) {
if (!formatters.containsKey(formatter)) {
BiFunction<Object, String, String> formatFunction = getFormatter(formatter);

if (formatFunction == null) {
throw new IllegalArgumentException(String.format(
"Unknown formatter `%s` found in format string: %s", formatter, state));
}

String result = formatters.get(formatter).apply(argument, state.indent);
String result = formatFunction.apply(argument, state.indent);

if (!state.eof() && state.c() == '@') {
if (startingBraceColumn == -1) {
Expand Down
178 changes: 159 additions & 19 deletions smithy-utils/src/main/java/software/amazon/smithy/utils/CodeWriter.java
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Original file line number Diff line number Diff line change
Expand Up @@ -85,8 +85,12 @@
* programming languages.</li>
* </ul>
*
* <p>Custom formatters can be registered using {@link #putFormatter}. The identifier
* given to a formatter must match the following ABNF:
* <p>Custom formatters can be registered using {@link #putFormatter}. 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 CodeWriter allows the formatter to be used in any state.
*
* <p>The identifier given to a formatter must match the following ABNF:
*
* <pre>
* %x21-23 ; ( '!' - '#' )
Expand Down Expand Up @@ -204,12 +208,12 @@
* 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, and the character used to start code
* expressions (defaults to {@code $}). State can be pushed onto the stack
* using {@link #pushState} which copies the current state. Mutations can then
* be made to the top-most state of the CodeWriter and do not affect previous
* states. The previous transformation state of the CodeWriter can later be
* restored using {@link #popState}.
* insertion of newlines is disabled, the character used to start code
* expressions (defaults to {@code $}), and formatters. State can be pushed onto
* the stack using {@link #pushState} which copies the current state. Mutations
* can then be made to the top-most state of the CodeWriter and do not affect
* previous states. The previous transformation state of the CodeWriter can later
* be restored using {@link #popState}.
*
* <p>The CodeWriter is stateful, and a prefix can be added before each line.
* This is useful for doing things like create Javadoc strings:
Expand Down Expand Up @@ -245,7 +249,6 @@
*
* <ul>
* <li>The number of successive blank lines to trim.</li>
* <li>Code formatters registered through {@link #putFormatter}</li>
* <li>Whether or not a trailing newline is inserted or removed from
* the result of converting the {@code CodeWriter} to a string.</li>
* </ul>
Expand Down Expand Up @@ -387,7 +390,6 @@ public class CodeWriter {
'L', (s, i) -> formatLiteral(s),
'S', (s, i) -> StringUtils.escapeJavaString(formatLiteral(s), i));

private final CodeFormatter formatter = new CodeFormatter();
private final Deque<State> states = new ArrayDeque<>();
private State currentState;
private boolean trailingNewline = true;
Expand All @@ -412,7 +414,6 @@ public CodeWriter() {
states.push(new State());
currentState = states.getFirst();
currentState.builder = new StringBuilder();
DEFAULT_FORMATTERS.forEach(formatter::putFormatter);
}

/**
Expand All @@ -427,6 +428,41 @@ public static CodeWriter createDefault() {
return new CodeWriter().trimTrailingSpaces();
}

/**
* Copies settings from the given CodeWriter into this CodeWriter.
*
* <p>The settings of the {@code other} CodeWriter will overwrite
* both global and state-based settings of this CodeWriter. Formatters of
* the {@code other} CodeWriter will be merged with the formatters of this
* CodeWriter, and in the case of conflicts, the formatters of the
* {@code other} will take precedence.
*
* <p>Stateful settings of the {@code other} CodeWriter are copied into
* the <em>current</em> state of this CodeWriter. Only the settings of
* the top-most state is copied. Other states, and the contents of the
* top-most state are not copied.
*
* <pre>{@code
* CodeWriter a = new CodeWriter();
* a.setExpressionStart('#');
*
* CodeWriter b = new CodeWriter();
* b.copySettingsFrom(a);
*
* assert(b.getExpressionStart() == '#');
* }</pre>
*
* @param other CodeWriter to copy settings from.
*/
public void copySettingsFrom(CodeWriter other) {
// Copy global settings.
trailingNewline = other.trailingNewline;
trimBlankLines = other.trimBlankLines;

// Copy the current state settings of other into the current state.
currentState.copyStateFrom(other.currentState);
}

/**
* Provides the default functionality for formatting literal values.
*
Expand Down Expand Up @@ -456,7 +492,8 @@ public static String formatLiteral(Object value) {
}

/**
* Adds a custom formatter expression to the {@code CodeWriter}.
* Adds a custom formatter expression to the current state of the
* {@code CodeWriter}.
*
* <p>The provided {@code identifier} string must match the following ABNF:
*
Expand All @@ -468,11 +505,14 @@ public static String formatLiteral(Object value) {
* </pre>
*
* @param identifier Formatter identifier to associate with this formatter.
* @param formatter Formatter function that formats the given object as a String.
* @param 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 CodeWriter.
* @return Returns the CodeWriter.
*/
public final CodeWriter putFormatter(char identifier, BiFunction<Object, String, String> formatter) {
this.formatter.putFormatter(identifier, formatter);
public final CodeWriter putFormatter(char identifier, BiFunction<Object, String, String> formatFunction) {
this.currentState.putFormatter(identifier, formatFunction);
return this;
}

Expand Down Expand Up @@ -849,6 +889,15 @@ public final CodeWriter setNewline(char newline) {
return setNewline(String.valueOf(newline));
}

/**
* Gets the character used to represent newlines in the current state.
*
* @return Returns the newline string.
*/
public String getNewline() {
return currentState.newline;
}

/**
* Sets the text used for indentation (defaults to four spaces).
*
Expand All @@ -860,6 +909,15 @@ public final CodeWriter setIndentText(String indentText) {
return this;
}

/**
* Gets the text used for indentation (defaults to four spaces).
*
* @return Returns the indentation string.
*/
public final String getIndentText() {
return currentState.indentText;
}

/**
* Enables the trimming of trailing spaces on a line.
*
Expand All @@ -880,6 +938,15 @@ public final CodeWriter trimTrailingSpaces(boolean trimTrailingSpaces) {
return this;
}

/**
* Returns true if the trailing spaces in the current state are trimmed.
*
* @return Returns the trailing spaces setting of the current state.
*/
public boolean getTrimTrailingSpaces() {
return currentState.trimTrailingSpaces;
}

/**
* Ensures that no more than one blank line occurs in succession.
*
Expand All @@ -904,6 +971,18 @@ public final CodeWriter trimBlankLines(int trimBlankLines) {
return this;
}

/**
* Returns the number of allowed consecutive newlines that are not
* trimmed by the CodeWriter when written to a string.
*
* @return Returns the number of allowed consecutive newlines. -1 means
* that no newlines are trimmed. 0 allows no blank lines. 1 or more
* allows for no more than N consecutive blank lines.
*/
public int getTrimBlankLines() {
return trimBlankLines;
}

/**
* Configures the CodeWriter to always append a newline at the end of
* the text if one is not already present.
Expand All @@ -922,7 +1001,7 @@ public final CodeWriter insertTrailingNewline() {
*
* <p>This setting is not captured as part of push/popState.
*
* @param trailingNewline The newline behavior. True to add, false to strip.
* @param trailingNewline True if a newline is added.
*
* @return Returns the CodeWriter.
*/
Expand All @@ -931,6 +1010,16 @@ public final CodeWriter insertTrailingNewline(boolean trailingNewline) {
return this;
}

/**
* Checks if the CodeWriter inserts a trailing newline (if necessary) when
* converted to a string.
*
* @return The newline behavior (true to insert a trailing newline).
*/
public boolean getInsertTrailingNewline() {
return trailingNewline;
}

/**
* Sets a prefix to prepend to every line after a new line is added
* (except for an inserted trailing newline).
Expand All @@ -943,6 +1032,16 @@ public final CodeWriter setNewlinePrefix(String newlinePrefix) {
return this;
}

/**
* Gets the prefix to prepend to every line after a new line is added
* (except for an inserted trailing newline).
*
* @return Returns the newline prefix string.
*/
public String getNewlinePrefix() {
return currentState.newlinePrefix;
}

/**
* Indents all text one level.
*
Expand All @@ -963,6 +1062,15 @@ public final CodeWriter indent(int levels) {
return this;
}

/**
* Gets the indentation level of the current state.
*
* @return Returns the indentation level of the current state.
*/
public int getIndentLevel() {
return currentState.indentation;
}

/**
* Removes one level of indentation from all lines.
*
Expand Down Expand Up @@ -1194,6 +1302,7 @@ public final CodeWriter writeWithNoFormatting(Object content) {
* @see #putFormatter
*/
public final String format(Object content, Object... args) {
CodeFormatter formatter = currentState.getCodeFormatter();
return formatter.format(currentState.expressionStart, content, currentState.indentText, this, args);
}

Expand Down Expand Up @@ -1389,6 +1498,12 @@ private final class State {
private String newline = "\n";
private char expressionStart = '$';

/** The formatter of the parent state (null for the root state). */
private CodeFormatter parentFormatter;

/** The formatter of the current state (null until a formatter is added to the state). */
private CodeFormatter stateFormatter;

private transient String sectionName;

/**
Expand All @@ -1409,12 +1524,22 @@ private final class State {
private Map<String, List<Consumer<Object>>> interceptors = MapUtils.of();
private transient boolean copiedInterceptors = false;

State() {}
State() {
// A state created without copying from another needs a root formatter that
// has all of the default formatter functions registered.
stateFormatter = new CodeFormatter();
DEFAULT_FORMATTERS.forEach(stateFormatter::putFormatter);
}

@SuppressWarnings("CopyConstructorMissesField")
State(State copy) {
copyStateFrom(copy);
this.builder = copy.builder;
}

private State(State copy) {
private void copyStateFrom(State copy) {
this.newline = copy.newline;
this.expressionStart = copy.expressionStart;
this.builder = copy.builder;
this.context = copy.context;
this.indentText = copy.indentText;
this.leadingIndentString = copy.leadingIndentString;
Expand All @@ -1423,13 +1548,28 @@ private State(State copy) {
this.trimTrailingSpaces = copy.trimTrailingSpaces;
this.interceptors = copy.interceptors;
this.disableNewline = copy.disableNewline;

// Copy the resolved formatter of "copy" as the parent formatter of this State.
this.parentFormatter = copy.getCodeFormatter();
}

@Override
public String toString() {
return builder == null ? "" : builder.toString();
}

private CodeFormatter getCodeFormatter() {
return stateFormatter != null ? stateFormatter : parentFormatter;
}

private void putFormatter(char identifier, BiFunction<Object, String, String> formatFunction) {
if (stateFormatter == null) {
stateFormatter = new CodeFormatter(parentFormatter);
}

stateFormatter.putFormatter(identifier, formatFunction);
}

private void mutateContext() {
if (!copiedContext) {
context = new HashMap<>(context);
Expand Down
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