[REF] owl: reorganize src code in sub files

src/qweb/expression_parser.ts

@@ -0,0 +1,264 @@
+/**
+ * Owl QWeb Expression Parser
+ *
+ * Owl needs in various contexts to be able to understand the structure of a
+ * string representing a javascript expression.  The usual goal is to be able
+ * to rewrite some variables.  For example, if a template has
+ *
+ *  ```xml
+ *  <t t-if="computeSomething({val: state.val})">...</t>
+ * ```
+ *
+ * this needs to be translated in something like this:
+ *
+ * ```js
+ *   if (context["computeSomething"]({val: context["state"].val})) { ... }
+ * ```
+ *
+ * This file contains the implementation of an extremely naive tokenizer/parser
+ * and evaluator for javascript expressions.  The supported grammar is basically
+ * only expressive enough to understand the shape of objects, of arrays, and
+ * various operators.
+ */
+
+//------------------------------------------------------------------------------
+// Misc types, constants and helpers
+//------------------------------------------------------------------------------
+
+const RESERVED_WORDS = "true,false,NaN,null,undefined,debugger,console,window,in,instanceof,new,function,return,this,typeof,eval,void,Math,RegExp,Array,Object,Date".split(
+  ","
+);
+
+const WORD_REPLACEMENT = {
+  and: "&&",
+  or: "||",
+  gt: ">",
+  gte: ">=",
+  lt: "<",
+  lte: "<="
+};
+
+export interface QWebExprVar {
+  id: string;
+  expr: string;
+}
+
+export interface QWebXMLVar {
+  xml: NodeList;
+}
+
+export type QWebVar = QWebExprVar | QWebXMLVar;
+
+//------------------------------------------------------------------------------
+// Tokenizer
+//------------------------------------------------------------------------------
+type TKind =
+  | "LEFT_BRACE"
+  | "RIGHT_BRACE"
+  | "LEFT_BRACKET"
+  | "RIGHT_BRACKET"
+  | "LEFT_PAREN"
+  | "RIGHT_PAREN"
+  | "COMMA"
+  | "VALUE"
+  | "SYMBOL"
+  | "OPERATOR"
+  | "COLON";
+
+interface Token {
+  type: TKind;
+  value: string;
+  size?: number;
+}
+
+const STATIC_TOKEN_MAP: { [key: string]: TKind } = {
+  "{": "LEFT_BRACE",
+  "}": "RIGHT_BRACE",
+  "[": "LEFT_BRACKET",
+  "]": "RIGHT_BRACKET",
+  ":": "COLON",
+  ",": "COMMA",
+  "(": "LEFT_PAREN",
+  ")": "RIGHT_PAREN"
+};
+
+const OPERATORS = ".,===,==,+,!==,!=,!,||,&&,>=,>,<=,<,?,-,*,/,%".split(",");
+
+type Tokenizer = (expr: string) => Token | false;
+
+let tokenizeString: Tokenizer = function(expr) {
+  let s = expr[0];
+  let start = s;
+  if (s !== "'" && s !== '"') {
+    return false;
+  }
+  let i = 1;
+  let cur;
+  while (expr[i] && expr[i] !== start) {
+    cur = expr[i];
+    s += cur;
+    if (cur === "\\") {
+      i++;
+      cur = expr[i];
+      if (!cur) {
+        throw new Error("Invalid expression");
+      }
+      s += cur;
+    }
+    i++;
+  }
+  if (expr[i] !== start) {
+    throw new Error("Invalid expression");
+  }
+  s += start;
+  return { type: "VALUE", value: s };
+};
+
+let tokenizeNumber: Tokenizer = function(expr) {
+  let s = expr[0];
+  if (s && s.match(/[0-9]/)) {
+    let i = 1;
+    while (expr[i] && expr[i].match(/[0-9]|\./)) {
+      s += expr[i];
+      i++;
+    }
+    return { type: "VALUE", value: s };
+  } else {
+    return false;
+  }
+};
+
+let tokenizeSymbol: Tokenizer = function(expr) {
+  let s = expr[0];
+  if (s && s.match(/[a-zA-Z_\$]/)) {
+    let i = 1;
+    while (expr[i] && expr[i].match(/\w/)) {
+      s += expr[i];
+      i++;
+    }
+    if (s in WORD_REPLACEMENT) {
+      return { type: "OPERATOR", value: WORD_REPLACEMENT[s], size: s.length };
+    }
+    return { type: "SYMBOL", value: s };
+  } else {
+    return false;
+  }
+};
+
+const tokenizeStatic: Tokenizer = function(expr) {
+  const char = expr[0];
+  if (char && char in STATIC_TOKEN_MAP) {
+    return { type: STATIC_TOKEN_MAP[char], value: char };
+  }
+  return false;
+};
+
+const tokenizeOperator: Tokenizer = function(expr) {
+  for (let op of OPERATORS) {
+    if (expr.startsWith(op)) {
+      return { type: "OPERATOR", value: op };
+    }
+  }
+  return false;
+};
+
+const TOKENIZERS = [
+  tokenizeString,
+  tokenizeNumber,
+  tokenizeSymbol,
+  tokenizeStatic,
+  tokenizeOperator
+];
+
+/**
+ * Convert a javascript expression (as a string) into a list of tokens. For
+ * example: `tokenize("1 + b")` will return:
+ * ```js
+ *  [
+ *   {type: "VALUE", value: "1"},
+ *   {type: "OPERATOR", value: "+"},
+ *   {type: "SYMBOL", value: "b"}
+ * ]
+ * ```
+ */
+export function tokenize(expr: string): Token[] {
+  const result: Token[] = [];
+  let token: boolean | Token = true;
+
+  while (token) {
+    expr = expr.trim();
+    if (expr) {
+      for (let tokenizer of TOKENIZERS) {
+        token = tokenizer(expr);
+        if (token) {
+          result.push(token);
+          expr = expr.slice(token.size || token.value.length);
+          break;
+        }
+      }
+    } else {
+      token = false;
+    }
+  }
+  if (expr.length) {
+    throw new Error(`Tokenizer error: could not tokenize "${expr}"`);
+  }
+  return result;
+}
+
+//------------------------------------------------------------------------------
+// Expression "evaluator"
+//------------------------------------------------------------------------------
+
+/**
+ * This is the main function exported by this file. This is the code that will
+ * process an expression (given as a string) and returns another expression with
+ * proper lookups in the context.
+ *
+ * Usually, this kind of code would be very simple to do if we had an AST (so,
+ * if we had a javascript parser), since then, we would only need to find the
+ * variables and replace them.  However, a parser is more complicated, and there
+ * are no standard builtin parser API.
+ *
+ * Since this method is applied to simple javasript expressions, and the work to
+ * be done is actually quite simple, we actually can get away with not using a
+ * parser, which helps with the code size.
+ *
+ * Here is the heuristic used by this method to determine if a token is a
+ * variable:
+ * - by default, all symbols are considered a variable
+ * - unless the previous token is a dot (in that case, this is a property: `a.b`)
+ * - or if the previous token is a left brace or a comma, and the next token is
+ *   a colon (in that case, this is an object key: `{a: b}`)
+ */
+export function compileExpr(expr: string, vars: { [key: string]: QWebVar }): string {
+  const tokens = tokenize(expr);
+  let result = "";
+  for (let i = 0; i < tokens.length; i++) {
+    let token = tokens[i];
+    if (token.type === "SYMBOL" && !RESERVED_WORDS.includes(token.value)) {
+      // we need to find if it is a variable
+      let isVar = true;
+      let prevToken = tokens[i - 1];
+      if (prevToken) {
+        if (prevToken.type === "OPERATOR" && prevToken.value === ".") {
+          isVar = false;
+        } else if (prevToken.type === "LEFT_BRACE" || prevToken.type === "COMMA") {
+          let nextToken = tokens[i + 1];
+          if (nextToken && nextToken.type === "COLON") {
+            isVar = false;
+          }
+        }
+      }
+      if (isVar) {
+        if (token.value in vars && "id" in vars[token.value]) {
+          token.value = (<QWebExprVar>vars[token.value]).id;
+        } else {
+          token.value = `context['${token.value}']`;
+        }
+      }
+    }
+    result += token.value;
+  }
+  return result;
+}