cheatsheet/src/data/examples/~lambdas.json

Cheatsheet boilerplate. Created for the new lesscss.org website, based on Shopify Cheat Sheet by Mark Dunkley.

{
  "ATTENTION": "Do not edit this file; changes belong in the appropriate YAML file.",
  "overview": "Lambdas are a special-cased data type for use in interpolations and\nsections.\n\nWhen used as the data value for an Interpolation tag, the lambda MUST be\ntreatable as an arity 0 function, and invoked as such.  The returned value\nMUST be rendered against the default delimiters, then interpolated in place\nof the lambda.\n\nWhen used as the data value for a Section tag, the lambda MUST be treatable\nas an arity 1 function, and invoked as such (passing a String containing the\nunprocessed section contents).  The returned value MUST be rendered against\nthe current delimiters, then interpolated in place of the section.\n",
  "tests": [
    {
      "name": "Interpolation",
      "data": {
        "lambda": {
          "php": "return \"world\";",
          "clojure": "(fn [] \"world\")",
          "__tag__": "code",
          "perl": "sub { \"world\" }",
          "python": "lambda: \"world\"",
          "ruby": "proc { \"world\" }",
          "js": "function() { return \"world\" }"
        }
      },
      "expected": "Hello, world!",
      "template": "Hello, {{lambda}}!",
      "desc": "A lambda's return value should be interpolated."
    },
    {
      "name": "Interpolation - Expansion",
      "data": {
        "planet": "world",
        "lambda": {
          "php": "return \"{{planet}}\";",
          "clojure": "(fn [] \"{{planet}}\")",
          "__tag__": "code",
          "perl": "sub { \"{{planet}}\" }",
          "python": "lambda: \"{{planet}}\"",
          "ruby": "proc { \"{{planet}}\" }",
          "js": "function() { return \"{{planet}}\" }"
        }
      },
      "expected": "Hello, world!",
      "template": "Hello, {{lambda}}!",
      "desc": "A lambda's return value should be parsed."
    },
    {
      "name": "Interpolation - Alternate Delimiters",
      "data": {
        "planet": "world",
        "lambda": {
          "php": "return \"|planet| => {{planet}}\";",
          "clojure": "(fn [] \"|planet| => {{planet}}\")",
          "__tag__": "code",
          "perl": "sub { \"|planet| => {{planet}}\" }",
          "python": "lambda: \"|planet| => {{planet}}\"",
          "ruby": "proc { \"|planet| => {{planet}}\" }",
          "js": "function() { return \"|planet| => {{planet}}\" }"
        }
      },
      "expected": "Hello, (|planet| => world)!",
      "template": "{{= | | =}}\nHello, (|&lambda|)!",
      "desc": "A lambda's return value should parse with the default delimiters."
    },
    {
      "name": "Interpolation - Multiple Calls",
      "data": {
        "lambda": {
          "php": "global $calls; return ++$calls;",
          "clojure": "(def g (atom 0)) (fn [] (swap! g inc))",
          "__tag__": "code",
          "perl": "sub { no strict; $calls += 1 }",
          "python": "lambda: globals().update(calls=globals().get(\"calls\",0)+1) or calls",
          "ruby": "proc { $calls ||= 0; $calls += 1 }",
          "js": "function() { return (g=(function(){return this})()).calls=(g.calls||0)+1 }"
        }
      },
      "expected": "1 == 2 == 3",
      "template": "{{lambda}} == {{{lambda}}} == {{lambda}}",
      "desc": "Interpolated lambdas should not be cached."
    },
    {
      "name": "Escaping",
      "data": {
        "lambda": {
          "php": "return \">\";",
          "clojure": "(fn [] \">\")",
          "__tag__": "code",
          "perl": "sub { \">\" }",
          "python": "lambda: \">\"",
          "ruby": "proc { \">\" }",
          "js": "function() { return \">\" }"
        }
      },
      "expected": "<&gt;>",
      "template": "<{{lambda}}{{{lambda}}}",
      "desc": "Lambda results should be appropriately escaped."
    },
    {
      "name": "Section",
      "data": {
        "x": "Error!",
        "lambda": {
          "php": "return ($text == \"{{x}}\") ? \"yes\" : \"no\";",
          "clojure": "(fn [text] (if (= text \"{{x}}\") \"yes\" \"no\"))",
          "__tag__": "code",
          "perl": "sub { $_[0] eq \"{{x}}\" ? \"yes\" : \"no\" }",
          "python": "lambda text: text == \"{{x}}\" and \"yes\" or \"no\"",
          "ruby": "proc { |text| text == \"{{x}}\" ? \"yes\" : \"no\" }",
          "js": "function(txt) { return (txt == \"{{x}}\" ? \"yes\" : \"no\") }"
        }
      },
      "expected": "<yes>",
      "template": "<{{#lambda}}{{x}}{{/lambda}}>",
      "desc": "Lambdas used for sections should receive the raw section string."
    },
    {
      "name": "Section - Expansion",
      "data": {
        "planet": "Earth",
        "lambda": {
          "php": "return $text . \"{{planet}}\" . $text;",
          "clojure": "(fn [text] (str text \"{{planet}}\" text))",
          "__tag__": "code",
          "perl": "sub { $_[0] . \"{{planet}}\" . $_[0] }",
          "python": "lambda text: \"%s{{planet}}%s\" % (text, text)",
          "ruby": "proc { |text| \"#{text}{{planet}}#{text}\" }",
          "js": "function(txt) { return txt + \"{{planet}}\" + txt }"
        }
      },
      "expected": "<-Earth->",
      "template": "<{{#lambda}}-{{/lambda}}>",
      "desc": "Lambdas used for sections should have their results parsed."
    },
    {
      "name": "Section - Alternate Delimiters",
      "data": {
        "planet": "Earth",
        "lambda": {
          "php": "return $text . \"{{planet}} => |planet|\" . $text;",
          "clojure": "(fn [text] (str text \"{{planet}} => |planet|\" text))",
          "__tag__": "code",
          "perl": "sub { $_[0] . \"{{planet}} => |planet|\" . $_[0] }",
          "python": "lambda text: \"%s{{planet}} => |planet|%s\" % (text, text)",
          "ruby": "proc { |text| \"#{text}{{planet}} => |planet|#{text}\" }",
          "js": "function(txt) { return txt + \"{{planet}} => |planet|\" + txt }"
        }
      },
      "expected": "<-{{planet}} => Earth->",
      "template": "{{= | | =}}<|#lambda|-|/lambda|>",
      "desc": "Lambdas used for sections should parse with the current delimiters."
    },
    {
      "name": "Section - Multiple Calls",
      "data": {
        "lambda": {
          "php": "return \"__\" . $text . \"__\";",
          "clojure": "(fn [text] (str \"__\" text \"__\"))",
          "__tag__": "code",
          "perl": "sub { \"__\" . $_[0] . \"__\" }",
          "python": "lambda text: \"__%s__\" % (text)",
          "ruby": "proc { |text| \"__#{text}__\" }",
          "js": "function(txt) { return \"__\" + txt + \"__\" }"
        }
      },
      "expected": "__FILE__ != __LINE__",
      "template": "{{#lambda}}FILE{{/lambda}} != {{#lambda}}LINE{{/lambda}}",
      "desc": "Lambdas used for sections should not be cached."
    },
    {
      "name": "Inverted Section",
      "data": {
        "static": "static",
        "lambda": {
          "php": "return false;",
          "clojure": "(fn [text] false)",
          "__tag__": "code",
          "perl": "sub { 0 }",
          "python": "lambda text: 0",
          "ruby": "proc { |text| false }",
          "js": "function(txt) { return false }"
        }
      },
      "expected": "<>",
      "template": "<{{^lambda}}{{static}}{{/lambda}}>",
      "desc": "Lambdas used for inverted sections should be considered truthy."
    }
  ]
}