update PA3: use our decaf.lowlevel

Author: paulzfm

build.sbt

@@ -15,6 +15,9 @@ libraryDependencies += "ch.qos.logback" % "logback-classic" % "1.2.3"
 
 libraryDependencies += "com.typesafe.scala-logging" %% "scala-logging" % "3.9.2"
 
+// https://mvnrepository.com/artifact/org.apache.commons/commons-lang3
+libraryDependencies += "org.apache.commons" % "commons-lang3" % "3.9"
+
 // antlr4
 
 enablePlugins(Antlr4Plugin)
@@ -28,3 +31,8 @@ antlr4GenVisitor in Antlr4 := true // default: false
 // assembly
 
 assemblyOutputPath in assembly := file("target/decaf.jar")
+
+// java 12
+
+javacOptions in Compile += "--enable-preview"
+javacOptions in Compile ++= Seq("-source", "12")

src/main/java/decaf/lowlevel/AsmCodePrinter.java

@@ -0,0 +1,126 @@
+package decaf.lowlevel;
+
+import decaf.lowlevel.instr.NativeInstr;
+import decaf.lowlevel.label.Label;
+
+/**
+ * Assembly code pretty printer.
+ */
+public class AsmCodePrinter {
+    private StringBuilder sb = new StringBuilder();
+
+    protected final String INDENTS = "    ";
+
+    protected final String END_LINE = "\n";
+
+    protected final String COMMENT_PROMPT = "#";
+
+    /**
+     * Format print, with indents.
+     *
+     * @param fmt  format
+     * @param args arguments
+     */
+    public void print(String fmt, Object... args) {
+        sb.append(INDENTS);
+        sb.append(String.format(fmt, args));
+    }
+
+    /**
+     * Format print a line, with indents.
+     *
+     * @param fmt  format
+     * @param args arguments
+     */
+    public void println(String fmt, Object... args) {
+        sb.append(INDENTS);
+        sb.append(String.format(fmt, args));
+        sb.append(END_LINE);
+    }
+
+    /**
+     * Simply print a newline.
+     */
+    public void println() {
+        sb.append(END_LINE);
+    }
+
+    /**
+     * Print a label.
+     *
+     * @param label label
+     */
+    public void printLabel(Label label) {
+        sb.append(label.name);
+        sb.append(":");
+        sb.append(END_LINE);
+    }
+
+    /**
+     * Print a label with comment.
+     *
+     * @param label   label
+     * @param comment comment
+     */
+    public void printLabel(Label label, String comment) {
+        sb.append(label.name);
+        sb.append(":");
+        sb.append("  ").append(COMMENT_PROMPT).append(' ').append(comment).append(END_LINE);
+    }
+
+    /**
+     * Print an instruction.
+     *
+     * @param instr instruction
+     */
+    public void printInstr(NativeInstr instr) {
+        if (instr.isLabel()) {
+            sb.append(instr.label);
+            sb.append(":");
+        } else {
+            sb.append(INDENTS);
+            sb.append(instr);
+        }
+
+        sb.append(END_LINE);
+    }
+
+    /**
+     * Print an instruction, with comment.
+     *
+     * @param instr   instruction
+     * @param comment comment
+     */
+    public void printInstr(NativeInstr instr, String comment) {
+        if (instr.isLabel()) {
+            sb.append(instr.label);
+            sb.append(":");
+        } else {
+            sb.append(INDENTS);
+            sb.append(instr);
+        }
+
+        sb.append("  ").append(COMMENT_PROMPT).append(' ').append(comment).append(END_LINE);
+    }
+
+    /**
+     * Print a comment.
+     *
+     * @param comment comment
+     */
+    public void printComment(String comment) {
+        sb.append(INDENTS);
+        sb.append(COMMENT_PROMPT).append(' ');
+        sb.append(comment);
+        sb.append(END_LINE);
+    }
+
+    /**
+     * Finish printing. Get the plain text of the assembly code.
+     *
+     * @return assembly code
+     */
+    public String close() {
+        return sb.toString();
+    }
+}