Start work diagnosticsparser

Signed-off-by: Antia Anderson <anita@ansan.io>

12 files changed, 373 insertions, 32 deletions

diff --git a/src/moe/anita/mai/buffer/Buffer.java b/src/moe/anita/mai/buffer/Buffer.java
index e119b40..1ed3cd6 100644
--- a/src/moe/anita/mai/buffer/Buffer.java
+++ b/src/moe/anita/mai/buffer/Buffer.java
@@ -5,6 +5,7 @@ package moe.anita.mai.buffer;
  */
 public interface Buffer {
 
+	String name();
 	/**
 	 * Returns the length of the underlying source representation.
 	 *
diff --git a/src/moe/anita/mai/buffer/MemBuf.java b/src/moe/anita/mai/buffer/MemBuf.java
index 922e624..7fb0c46 100644
--- a/src/moe/anita/mai/buffer/MemBuf.java
+++ b/src/moe/anita/mai/buffer/MemBuf.java
@@ -10,13 +10,21 @@ import java.util.Objects;
  */
 public final class MemBuf implements Buffer {
 
+	private final String name;
 	private final byte[] data;
 
 	public MemBuf(String source) {
-		Objects.requireNonNull(source);
-		data = source.getBytes(StandardCharsets.UTF_8);
+		this("<memory>", source);
 	}
 
+	public MemBuf(String name, String source) {
+		this.name = name;
+		this.data = source.getBytes(StandardCharsets.UTF_8);
+	}
+
+	@Override
+	public String name() { return name; }
+
 	@Override
 	public int length() {
 		return data.length;
diff --git a/src/moe/anita/mai/buffer/SrcBuf.java b/src/moe/anita/mai/buffer/SrcBuf.java
index f288316..f0e3296 100644
--- a/src/moe/anita/mai/buffer/SrcBuf.java
+++ b/src/moe/anita/mai/buffer/SrcBuf.java
@@ -16,11 +16,9 @@ public final class SrcBuf implements Buffer {
 		this.data = Files.readString(path, StandardCharsets.UTF_8);
 	}
 
-	/**
-	 * Returns the source file path.
-	 *
-	 * @return source path
-	 */
+	@Override
+	public String name() { return path.getFileName().toString(); }
+
 	public Path path() {
 		return path;
 	}
diff --git a/src/moe/anita/mai/diag/ColorMode.java b/src/moe/anita/mai/diag/ColorMode.java
new file mode 100644
index 0000000..ebb31b8
--- /dev/null
+++ b/src/moe/anita/mai/diag/ColorMode.java
@@ -0,0 +1,7 @@
+package moe.anita.mai.diag;
+
+public enum ColorMode {
+	AUTO,
+	ALWAYS,
+	NEVER,
+}
diff --git a/src/moe/anita/mai/diag/ConsolePrinter.java b/src/moe/anita/mai/diag/ConsolePrinter.java
new file mode 100644
index 0000000..0c8e051
--- /dev/null
+++ b/src/moe/anita/mai/diag/ConsolePrinter.java
@@ -0,0 +1,150 @@
+package moe.anita.mai.diag;
+
+import moe.anita.mai.buffer.Buffer;
+import moe.anita.mai.span.Line;
+import moe.anita.mai.span.Lines;
+import moe.anita.mai.span.Pos;
+import moe.anita.mai.span.Span;
+
+import java.io.PrintStream;
+
+public class ConsolePrinter implements Printer {
+
+	private static final String RESET = "\033[0m";
+	private static final String BOLD = "\033[1m";
+
+	private static final String RED = "\033[31m";
+	private static final String YELLOW = "\033[33m";
+	private static final String CYAN = "\033[36m";
+
+	private final PrintStream out;
+	private final boolean color;
+
+	public ConsolePrinter(PrintStream out, ColorMode colorMode) {
+		this.out = out;
+		this.color = useColor(colorMode);
+	}
+
+	@Override
+	public void print(Buffer source, Diagnostic diagnostic) {
+		Span span = diagnostic.span();
+		Pos start = span.start();
+		Line line = Lines.at(source, start);
+
+		printHeader(diagnostic);
+		printLocation(source, start);
+		printSource(line, diagnostic);
+	}
+
+	private void printHeader(Diagnostic diagnostic) {
+		printLevel(diagnostic.level());
+		out.print(": ");
+		out.println(diagnostic.msg());
+	}
+
+	private void printLocation(Buffer source, Pos pos) {
+		out.print("  --> ");
+
+		if (color) {
+			out.print(CYAN);
+		}
+
+		out.printf("%s:%d:%d", source.name(), pos.line(), pos.column());
+
+		if (color) {
+			out.print(RESET);
+		}
+
+		out.println();
+	}
+
+	private void printSource(Line line, Diagnostic diagnostic) {
+		int gutterWidth = digits(line.number());
+
+		out.printf("%" + gutterWidth + "s |%n", "");
+		out.printf("%" + gutterWidth + "d | %s%n", line.number(), line.text());
+
+		printMarker(line, diagnostic, gutterWidth);
+
+		out.printf("%" + gutterWidth + "s |%n", "");
+	}
+
+	private void printMarker(Line line, Diagnostic diagnostic, int gutterWidth) {
+		Span span = diagnostic.span();
+		int startColumn = span.start().column();
+		int width = markerWidth(span, line);
+
+		out.printf("%" + gutterWidth + "s | ", "");
+		out.print(" ".repeat(Math.max(0, startColumn - 1)));
+
+		beginLevelStyle(diagnostic.level());
+
+		out.print("^".repeat(width));
+
+		if (diagnostic.label() != null && !diagnostic.label().isEmpty()) {
+			out.print(" ");
+			out.print(diagnostic.label());
+		}
+
+		endStyle();
+		out.println();
+	}
+
+	private int markerWidth(Span span, Line line) {
+		if (span.start().line() != span.end().line()) {
+			return Math.max(1, line.text().codePointCount(0, line.text().length()) - span.start().column() + 2);
+		}
+
+		return Math.max(1, span.end().column() - span.start().column());
+	}
+
+	private void printLevel(Diagnostic.Level level) {
+		beginLevelStyle(level);
+		out.print(levelName(level));
+		endStyle();
+	}
+
+	private void beginLevelStyle(Diagnostic.Level level) {
+		if (!color) {
+			return;
+		}
+
+		out.print(BOLD);
+		out.print(levelColor(level));
+	}
+
+	private void endStyle() {
+		if (color) {
+			out.print(RESET);
+		}
+	}
+
+	private String levelName(Diagnostic.Level level) {
+		return switch (level) {
+			case ERROR -> "error";
+			case WARNING -> "warning";
+			case NOTE -> "note";
+			case HELP -> "help";
+		};
+	}
+
+	private String levelColor(Diagnostic.Level level) {
+		return switch (level) {
+			case ERROR -> RED;
+			case WARNING -> YELLOW;
+			case NOTE, HELP -> CYAN;
+		};
+	}
+
+	private int digits(int value) {
+		return Integer.toString(value).length();
+	}
+
+	private boolean useColor(ColorMode mode) {
+		return switch (mode) {
+			case ALWAYS -> true;
+			case NEVER -> false;
+			case AUTO -> System.console() != null;
+		};
+	}
+}
diff --git a/src/moe/anita/mai/diag/Diagnostic.java b/src/moe/anita/mai/diag/Diagnostic.java
new file mode 100644
index 0000000..da1d92b
--- /dev/null
+++ b/src/moe/anita/mai/diag/Diagnostic.java
@@ -0,0 +1,13 @@
+package moe.anita.mai.diag;
+
+import moe.anita.mai.span.Span;
+
+public record Diagnostic(Level level, String msg, Span span, String label) {
+
+	public enum Level {
+		ERROR,
+		WARNING,
+		NOTE,
+		HELP
+	}
+}
diff --git a/src/moe/anita/mai/diag/JsonPrinter.java b/src/moe/anita/mai/diag/JsonPrinter.java
new file mode 100644
index 0000000..5aceab4
--- /dev/null
+++ b/src/moe/anita/mai/diag/JsonPrinter.java
@@ -0,0 +1,115 @@
+package moe.anita.mai.diag;
+
+import java.io.PrintStream;
+
+import moe.anita.mai.buffer.Buffer;
+import moe.anita.mai.span.Pos;
+import moe.anita.mai.span.Span;
+
+/**
+ * Prints diagnostics as newline-delimited JSON.
+ */
+public final class JsonPrinter implements Printer {
+
+	private final PrintStream out;
+
+	public JsonPrinter(PrintStream out) {
+		this.out = out;
+	}
+
+	@Override
+	public void print(Buffer source, Diagnostic diagnostic) {
+		Span span = diagnostic.span();
+
+		out.print('{');
+
+		field("source", source.name());
+		out.print(',');
+
+		field("level", levelName(diagnostic.level()));
+		out.print(',');
+
+		field("message", diagnostic.msg());
+
+		if (diagnostic.label() != null && !diagnostic.label().isEmpty()) {
+			out.print(',');
+			field("label", diagnostic.label());
+		}
+
+		out.print(',');
+		out.print("\"span\":");
+
+		printSpan(span);
+
+		out.println('}');
+	}
+
+	private void printSpan(Span span) {
+		out.print('{');
+
+		out.print("\"start\":");
+		printPos(span.start());
+
+		out.print(',');
+
+		out.print("\"end\":");
+		printPos(span.end());
+
+		out.print('}');
+	}
+
+	private void printPos(Pos pos) {
+		out.print('{');
+
+		out.printf("\"offset\":%d,", pos.offset());
+		out.printf("\"line\":%d,", pos.line());
+		out.printf("\"column\":%d", pos.column());
+
+		out.print('}');
+	}
+
+	private void field(String name, String value) {
+		out.print('"');
+		out.print(escape(name));
+		out.print("\":\"");
+		out.print(escape(value));
+		out.print('"');
+	}
+
+	private String levelName(Diagnostic.Level level) {
+		return switch (level) {
+			case ERROR -> "error";
+			case WARNING -> "warning";
+			case NOTE -> "note";
+			case HELP -> "help";
+		};
+	}
+
+	private String escape(String value) {
+		var result = new StringBuilder(value.length());
+
+		for (int i = 0; i < value.length(); i++) {
+			char c = value.charAt(i);
+
+			switch (c) {
+				case '"' -> result.append("\\\"");
+				case '\\' -> result.append("\\\\");
+				case '\b' -> result.append("\\b");
+				case '\f' -> result.append("\\f");
+				case '\n' -> result.append("\\n");
+				case '\r' -> result.append("\\r");
+				case '\t' -> result.append("\\t");
+
+				default -> {
+					if (c < 0x20) {
+						result.append("\\u%04x".formatted((int) c));
+					} else {
+						result.append(c);
+					}
+				}
+			}
+		}
+
+		return result.toString();
+	}
+}
diff --git a/src/moe/anita/mai/diag/Printer.java b/src/moe/anita/mai/diag/Printer.java
new file mode 100644
index 0000000..21234e9
--- /dev/null
+++ b/src/moe/anita/mai/diag/Printer.java
@@ -0,0 +1,8 @@
+package moe.anita.mai.diag;
+
+import moe.anita.mai.buffer.Buffer;
+
+@FunctionalInterface
+public interface Printer {
+	void print(Buffer buf, Diagnostic diagnostic);
+}
diff --git a/src/moe/anita/mai/span/Line.java b/src/moe/anita/mai/span/Line.java
new file mode 100644
index 0000000..3afb9c2
--- /dev/null
+++ b/src/moe/anita/mai/span/Line.java
@@ -0,0 +1,4 @@
+package moe.anita.mai.span;
+
+public record Line(int number, int start, int end, String text) {
+}
diff --git a/src/moe/anita/mai/span/Lines.java b/src/moe/anita/mai/span/Lines.java
new file mode 100644
index 0000000..e1e27d1
--- /dev/null
+++ b/src/moe/anita/mai/span/Lines.java
@@ -0,0 +1,40 @@
+package moe.anita.mai.span;
+
+import moe.anita.mai.buffer.Buffer;
+
+public final class Lines {
+
+	public static Line at(Buffer buf, Pos pos) {
+		int start = lineStart(buf, pos.offset());
+		int end   = lineEnd(buf, pos.offset());
+		return new Line(pos.line(), start , end, buf.slice(start, end).toString());
+	}
+
+	private static int lineStart(Buffer buf, int offset) {
+		int current  = 0;
+		int previous = 0;
+
+		while (current < offset) {
+			if (buf.get(current) == '\n') {
+				previous = current + buf.width(current);
+			}
+			current += buf.width(current);
+		}
+		return previous;
+	}
+
+	public static int lineEnd(Buffer buf, int offset) {
+		int current = offset;
+
+		while (current < buf.length()) {
+			if (buf.get(current) == '\n') {
+				return current;
+			}
+			current += buf.width(current);
+		}
+
+		return buf.length();
+	}
+
+	private Lines() {}
+}
diff --git a/src/moe/anita/mai/span/Pos.java b/src/moe/anita/mai/span/Pos.java
index 4b129e2..17685ab 100644
--- a/src/moe/anita/mai/span/Pos.java
+++ b/src/moe/anita/mai/span/Pos.java
@@ -19,28 +19,12 @@ public final class Pos {
 		return new Pos(value);
 	}
 
-	public static Pos zero() {
-		return new Pos(0);
-	}
-
-	public int offset() {
-		return (int) ((value >>> 32) & OFFSET_MASK);
-	}
-
-	public int line() {
-		return (int) ((value >>> 16) & U16_MASK);
-	}
-
-	public int column() {
-		return (int) (value & U16_MASK);
-	}
-
-	public boolean isZero() {
-		return value == 0;
-	}
+	public static Pos zero() { return new Pos(0); }
+	public int offset() { return (int) ((value >>> 32) & OFFSET_MASK); }
+	public int line() { return (int) ((value >>> 16) & U16_MASK); }
+	public int column() { return (int) (value & U16_MASK); }
+	public boolean isZero() { return value == 0; }
 
 	@Override
-	public String toString() {
-		return "%d:%d".formatted(line(), column());
-	}
+	public String toString() { return "%d:%d".formatted(line(), column()); }
 }
diff --git a/src/moe/anita/mai/span/Span.java b/src/moe/anita/mai/span/Span.java
index fe27a91..4ab40cd 100644
--- a/src/moe/anita/mai/span/Span.java
+++ b/src/moe/anita/mai/span/Span.java
@@ -1,5 +1,7 @@
 package moe.anita.mai.span;
 
+import java.util.Objects;
+
 public final class Span {
 
 	private final Pos start;
@@ -38,8 +40,19 @@ public final class Span {
 		return start.isZero() && end.isZero();
 	}
 
-	@Override
-	public String toString() {
-		return "%s-%s".formatted(start, end);
+	public boolean contains(int offset) {
+		return offset >= start.offset() && offset < end.offset();
+	}
+
+	public Span merge(Span other) {
+		Objects.requireNonNull(other);
+
+		Pos mergedStart = start.offset() <= other.start.offset() ? start : other.start;
+		Pos mergedEnd = end.offset() >= other.end.offset() ? end : other.end;
+
+		return new Span(mergedStart, mergedEnd);
 	}
+
+	@Override
+	public String toString() { return "%s-%s".formatted(start, end); }
 }