Parses a statement if ( expression ) statement [else statement] @return a Node, never null
()
| 264 | * @return a {@link Node}, never {@code null} |
| 265 | */ |
| 266 | private Node parseIf() { |
| 267 | require("("); |
| 268 | // Parse predicate |
| 269 | var pred = require(parseExpression(), ")"); |
| 270 | // IfNode takes current control and predicate |
| 271 | Node ifNode = new IfNode(ctrl(), pred).peephole(); |
| 272 | // Setup projection nodes |
| 273 | Node ifT = new ProjNode(ifNode. keep(), 0, "True" ).peephole().keep(); |
| 274 | Node ifF = new ProjNode(ifNode.unkeep(), 1, "False").peephole().keep(); |
| 275 | // In if true branch, the ifT proj node becomes the ctrl |
| 276 | // But first clone the scope and set it as current |
| 277 | int ndefs = _scope.nIns(); |
| 278 | ScopeNode fScope = _scope.dup(); // Duplicate current scope |
| 279 | _xScopes.push(fScope); // For graph visualization we need all scopes |
| 280 | |
| 281 | // Parse the true side |
| 282 | ctrl(ifT.unkeep()); // set ctrl token to ifTrue projection |
| 283 | parseStatement(); // Parse true-side |
| 284 | ScopeNode tScope = _scope; |
| 285 | |
| 286 | // Parse the false side |
| 287 | _scope = fScope; // Restore scope, then parse else block if any |
| 288 | ctrl(ifF.unkeep()); // Ctrl token is now set to ifFalse projection |
| 289 | if (matchx("else")) { |
| 290 | parseStatement(); |
| 291 | fScope = _scope; |
| 292 | } |
| 293 | |
| 294 | if( tScope.nIns() != ndefs || fScope.nIns() != ndefs ) |
| 295 | throw error("Cannot define a new name on one arm of an if"); |
| 296 | |
| 297 | // Merge results |
| 298 | _scope = tScope; |
| 299 | _xScopes.pop(); // Discard pushed from graph display |
| 300 | |
| 301 | return ctrl(tScope.mergeScopes(fScope)); |
| 302 | } |
| 303 | |
| 304 | |
| 305 | /** |
no test coverage detected