Unpolished translation of Styler.coffee

src/Styler.coffee

@@ -1,112 +0,0 @@
-###
-  termap - Terminal Map Viewer
-  by Michael Strassburger <codepoet@cpan.org>
-
-  Minimalistic parser and compiler for Mapbox (Studio) Map Style files
-  See: https://www.mapbox.com/mapbox-gl-style-spec/
-
-  Compiles layer filter instructions into a chain of true/false returning
-  anonymous functions to improve rendering speed compared to realtime parsing.
-###
-
-fs = require 'fs'
-
-module.exports = class Styler
-  styleById: {}
-  styleByLayer: {}
-
-  constructor: (file) ->
-    json = JSON.parse fs.readFileSync(file).toString()
-    @styleName = json.name
-
-    @_replaceConstants json.constants, json.layers if json.constants
-
-    for style in json.layers
-      if style.ref and @styleById[style.ref]
-        for ref in ['type', 'source-layer', 'minzoom', 'maxzoom', 'filter']
-          if @styleById[style.ref][ref] and not style[ref]
-            style[ref] = @styleById[style.ref][ref]
-
-      style.appliesTo = @_compileFilter style.filter
-
-      @styleByLayer[style['source-layer']] ?= []
-      @styleByLayer[style['source-layer']].push style
-      @styleById[style.id] = style
-
-  getStyleFor: (layer, feature, zoom) ->
-    return false unless @styleByLayer[layer]
-
-    for style in @styleByLayer[layer]
-      if style.appliesTo feature
-          return style
-
-    return false
-
-  _replaceConstants: (constants, tree) ->
-    for id, node of tree
-      switch typeof node
-        when 'object'
-          continue if node.constructor.name.match /Stream/
-          @_replaceConstants constants, node
-
-        when 'string'
-          if node.charAt(0) is '@'
-            tree[id] = constants[node]
-    null
-
-  _compileFilter: (filter) ->
-    switch filter?[0]
-      when "all"
-        filters = (@_compileFilter subFilter for subFilter in filter[1..])
-        (feature) ->
-          return false for appliesTo in filters when not appliesTo feature
-          true
-
-      when "any"
-        filters = (@_compileFilter subFilter for subFilter in filter[1..])
-        (feature) ->
-          return true for appliesTo in filters when appliesTo feature
-          false
-
-      when "none"
-        filters = (@_compileFilter subFilter for subFilter in filter[1..])
-        (feature) ->
-          return false for appliesTo in filters when appliesTo feature
-          true
-
-      when "=="
-        (feature) -> feature.properties[filter[1]] is filter[2]
-
-      when "!="
-        (feature) -> feature.properties[filter[1]] isnt filter[2]
-
-      when "in"
-        (feature) ->
-          return true for value in filter[2..] when feature.properties[filter[1]] is value
-          false
-
-      when "!in"
-        (feature) ->
-          return false for value in filter[2..] when feature.properties[filter[1]] is value
-          true
-
-      when "has"
-        (feature) -> !!feature.properties[filter[1]]
-
-      when "!has"
-        (feature) -> !feature.properties[filter[1]]
-
-      when ">"
-        (feature) -> feature.properties[filter[1]] > filter[2]
-
-      when ">="
-        (feature) -> feature.properties[filter[1]] >= filter[2]
-
-      when "<"
-        (feature) -> feature.properties[filter[1]] < filter[2]
-
-      when "<="
-        (feature) -> feature.properties[filter[1]] <= filter[2]
-
-      else
-        -> true

src/Styler.js

@@ -0,0 +1,163 @@
+/*
+  termap - Terminal Map Viewer
+  by Michael Strassburger <codepoet@cpan.org>
+
+  Minimalistic parser and compiler for Mapbox (Studio) Map Style files
+  See: https://www.mapbox.com/mapbox-gl-style-spec/
+
+  Compiles layer filter instructions into a chain of true/false returning
+  anonymous functions to improve rendering speed compared to realtime parsing.
+*/
+var Styler;
+
+const fs = require('fs');
+
+module.exports = class Styler {
+  constructor(file) {
+    this.styleById = {};
+    this.styleByLayer = {};
+    var base, name;
+    const json = JSON.parse(fs.readFileSync(file).toString());
+    this.styleName = json.name;
+    if (json.constants) {
+      this._replaceConstants(json.constants, json.layers);
+    }
+
+    for (const style of json.layers) {
+      if (style.ref && this.styleById[style.ref]) {
+        for (const ref of ['type', 'source-layer', 'minzoom', 'maxzoom', 'filter']) {
+          if (this.styleById[style.ref][ref] && !style[ref]) {
+            style[ref] = this.styleById[style.ref][ref];
+          }
+        }
+      }
+
+      style.appliesTo = this._compileFilter(style.filter);
+
+      //TODO Better translation of: @styleByLayer[style['source-layer']] ?= []
+      if ((base = this.styleByLayer)[name = style['source-layer']] == null) {
+        base[name] = [];
+      }
+      this.styleByLayer[style['source-layer']].push(style);
+      this.styleById[style.id] = style;
+    }
+  }
+
+  getStyleFor(layer, feature, zoom) {
+    if (!this.styleByLayer[layer]) {
+      return false;
+    }
+
+    for (const style of this.styleByLayer[layer]) {
+      if (style.appliesTo(feature)) {
+        return style;
+      }
+    }
+
+    return false;
+  }
+
+  _replaceConstants(constants, tree) {
+    for (const id in tree) {
+      const node = tree[id];
+      switch (typeof node) {
+        case 'object':
+          if (node.constructor.name.match(/Stream/)) {
+            continue;
+          }
+          this._replaceConstants(constants, node);
+          break;
+        case 'string':
+          if (node.charAt(0) === '@') {
+            tree[id] = constants[node];
+          }
+      }
+    }
+  }
+
+  //TODO Better translation of the long cases.
+  _compileFilter(filter) {
+    var filters;
+    switch (filter != null ? filter[0] : void 0) {
+      case 'all':
+        filter = filter.slice(1);
+        filters = (() => {
+          return filter.map((sub) => this._compileFilter(sub));
+        }).call(this);
+        //TODO Use Array.prototype.find
+        return (feature) => {
+          for (const appliesTo of filters) {
+            if (!appliesTo(feature)) {
+              return false;
+            }
+          }
+          return true;
+        };
+      case 'any':
+        filter = filter.slice(1);
+        filters = (() => {
+          return filter.map((sub) => this._compileFilter(sub));
+        }).call(this);
+        //TODO Use Array.prototype.find
+        return (feature) => {
+          for (const appliesTo of filters) {
+            if (appliesTo(feature)) {
+              return true;
+            }
+          }
+          return false;
+        };
+      case 'none':
+        filter = filter.slice(1);
+        filters = (() => {
+          return filter.map((sub) => this._compileFilter(sub));
+        }).call(this);
+        return (feature) => {
+          for (const appliesTo of filters) {
+            if (appliesTo(feature)) {
+              return false;
+            }
+          }
+          return true;
+        };
+      case '==':
+        return (feature) => feature.properties[filter[1]] === filter[2];
+      case "!=":
+        return (feature) => feature.properties[filter[1]] !== filter[2];
+      case "in":
+        return (feature) => {
+          filter = filter.slice(2);
+          for (const value of filter) {
+            if (feature.properties[filter[1]] === value) {
+              return true;
+            }
+          }
+          return false;
+        };
+      case '!in':
+        return (feature) => {
+          filter = filter.slice(2);
+          for (const value of filter) {
+            if (feature.properties[filter[1]] === value) {
+              return false;
+            }
+          }
+          return true;
+        };
+      case "has":
+        return (feature) => !!feature.properties[filter[1]];
+      case "!has":
+        return (feature) => !feature.properties[filter[1]];
+      case ">":
+        return (feature) => feature.properties[filter[1]] > filter[2];
+      case ">=":
+        return (feature) => feature.properties[filter[1]] >= filter[2];
+      case "<":
+        return (feature) => feature.properties[filter[1]] < filter[2];
+      case "<=":
+        return (feature) => feature.properties[filter[1]] <= filter[2];
+      default:
+        return () => true;
+    }
+  }
+}