Forgot to check this in last time

Author: mike-lang

controlAndBooleanExpressions.js

@@ -0,0 +1,306 @@
+'use strict';
+
+const cradle = require('./cradle'),
+  expressionParsing = require('./expression');
+
+
+const q = require('q');
+
+const emitLn = cradle.emitLn,
+  getName = cradle.getName,
+  init = cradle.init,
+  look = cradle.look,
+  expected = cradle.expected,
+  match = cradle.match,
+  abort = cradle.abort,
+  expression = expressionParsing.expression,
+  boolExpression = expressionParsing.boolExpression;
+
+let labelCount = 0;
+
+function newLabel() {
+  let result = 'L' + labelCount;
+  labelCount++;
+  return result;
+}
+
+function postLabel(l) {
+  console.log(l + ':');
+}
+
+function other() {
+  return getName()
+    .then((name) => {
+      emitLn(name);
+    });
+}
+
+function doFor() {
+  let label1, label2, counterName;
+
+  return match('f')
+    .then(() => {
+      label1 = newLabel();
+      label2 = newLabel();
+      return getName();
+    })
+    .then((name) => {
+      counterName = name;
+      return match('=');
+    })
+    .then(() => {
+      return expression();
+    })
+    .then(() => {
+      emitLn('SUBQ #1,D0');
+      emitLn('LEA ' + counterName + '(PC),A0');
+      emitLn('MOVE D0,(A0)');
+      return expression();
+    })
+    .then(() => {
+      emitLn('MOVE D0,-(SP)');
+      postLabel(label1);
+      emitLn('LEA ' + counterName + '(PC),A0');
+      emitLn('MOVE (A0),D0');
+      emitLn('ADDQ #1,D0');
+      emitLn('MOVE D0,(A0)');
+      emitLn('CMP (SP),D0');
+      emitLn('BGT ' + label2);
+      return block(label2);
+    })
+    .then(() => {
+      return match('e');
+    })
+    .then(() => {
+      emitLn('BRA ' + label1);
+      postLabel(label2);
+      emitLn('ADDQ #2,SP');
+    })
+
+
+}
+
+function block(exitLabel) {
+  function continueBlock() {
+    return fin()
+      .then(() => {
+        return block(exitLabel);
+      })
+  };
+  return q()
+    .then(() => {
+      const c = look();
+      if (c !== 'e' && c !== 'l' && c !== 'u') {
+        return fin()
+          .then(() => {
+            switch(c) {
+              case 'i': 
+                return doIf(exitLabel)
+                  .then(continueBlock);
+              case 'w':
+                return doWhile()
+                  .then(continueBlock);
+              case 'p':
+                return doLoop()
+                  .then(continueBlock);
+              case 'r':
+                return doRepeat()
+                  .then(continueBlock);
+              case 'f':
+                return doFor()
+                  .then(continueBlock);
+              case 'd':
+                return doDo()
+                  .then(continueBlock);
+              case 'b': 
+                return doBreak(exitLabel)
+                  .then(continueBlock);
+              default:
+                return other()
+                  .then(continueBlock);
+            }
+          });
+      }
+    });
+}
+
+function doIf(loopExitLabel) {
+  let label1, label2;
+
+  return match('i')
+    .then(() => {
+      label1 = newLabel();
+      label2 = label1;
+      return boolExpression();
+    })
+    .then(() => {
+      emitLn('BEQ ' + label1);
+      return block();
+    })
+    .then(() => {
+      let nextChar = look();
+      if (nextChar === 'l') {
+        return match('l')
+          .then(() => {
+            label2 = newLabel();
+            emitLn('BRA ' + label2);
+            postLabel(label1);
+            return block(loopExitLabel);
+          });
+      }
+    }).then(() => {
+      return match('e');
+    })
+    .then(() => {
+      postLabel(label2);
+    });
+}
+
+function doBreak(label) {
+  return match('b')
+    .then(() => {
+      if (label !== '') {
+        emitLn('BRA ' + label);
+      } else {
+        abort('No loop to break from');
+      }
+    });
+}
+
+function doWhile() {
+  let label1, label2;
+
+  return match('w')
+    .then(() => {
+      label1 = newLabel();
+      label2 = newLabel();
+      postLabel(label1);
+      return boolExpression();
+    })
+    .then(() => {
+      emitLn('BEQ ' + label2);
+      return block(label2);
+    })
+    .then(() => {
+      return match('e');
+    })
+    .then(() => {
+      emitLn('BRA ' + label1);
+      postLabel(label2);
+    });
+}
+
+function doLoop() {
+  let label1, label2;
+  return match('p')
+    .then(() => {
+      label1 = newLabel();
+      label2 = newLabel();
+      postLabel(label1);
+      return block(label2);
+    })
+    .then(() => {
+      return match('e');
+    })
+    .then(() => {
+      emitLn('BRA ' + label1);
+      postLabel(label2);
+    });
+}
+
+function doRepeat() {
+  let label1, label2;
+  return match('r')
+    .then(() => {
+      label1 = newLabel();
+      label2 = newLabel();
+      postLabel(label1);
+      return block(label2);
+    })
+    .then(() => {
+      return match('u');
+    })
+    .then(() => {
+      return boolExpression();
+    })
+    .then(() => {
+      emitLn('BEQ ' + label1);
+      postLabel(label2);
+    });
+}
+
+function doDo() {
+  let label1, label2;
+  return match('d')
+    .then(() => {
+      label1 = newLabel();
+      label2 = newLabel();
+      return expression();
+    })
+    .then(() => {
+      emitLn('SUBQ #1,D0');
+      postLabel(label1);
+      emitLn('MOVE D0,-(SP)');
+      return block(label2);
+    })
+    .then(() => {
+      emitLn('MOVE (SP)+,D0');
+      emitLn('DBRA D0,' + label);
+      emitLn('SUBQ #2,SP');
+      postLabel(label2);
+      emitLn('ADDQ #2,SP');
+    });
+}
+
+function doProgram() {
+  return block('')
+    .then(() => {
+      const c = look();
+      if (c !== 'e') return expected('End');
+      emitLn('END');
+    });
+}
+
+function fin() {
+  return q()
+    .then(() => {
+      let nextChar = look();
+      if (nextChar === '\r') 
+        return getChar();
+    })
+    .then(() => {
+      let nextChar = look();
+      if (nextChar === '\n')
+        return getChar();
+    });
+}
+
+function assignment() {
+  // Somewhere we need to generate DS directives
+  // for this to work with the EASy68K assembler.
+  // Leaving this as an exercise for now to collect variables
+  // and collect generated code in a buffer so that
+  // the appropriate header with symbol definitions
+  // is put before the code in the results emitted
+  // on stdout
+  return getName()
+    .then((name) => {
+      return match('=')
+        .then(() => {
+          return boolExpression()
+            .then(() => {
+              emitLn('LEA ' + name + '(PC),A0');
+              emitLn('MOVE D0,(A0)');
+            });
+        });
+    });
+}
+
+
+init()
+  .then(() => {
+    return doProgram();
+  })
+  .catch((err) => {
+    console.log(err.stack);
+  });