Generate a series of nested switch statements to parse CSSPrimitiveValue units.

third_party/WebKit/Source/build/scripts/templates/macros.tmpl

 {#
     FIXME: Do we need to put license blocks in generated files?
 #}
 {% macro license() %}
 // Copyright (c) 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 {%- endmacro %}
+
+{% macro trie_leaf(index, entry, return_macro, default_return_value) %}

[Timothy Loh, 2016/05/03 07:40:25]

We'll need a flag should_lower since unlike the tag names the dimension units
are not already lower case. Also it's potentially simpler to get rid of
return_macro and make the values stored in the tried the actual return values.

+{% if entry.conditions %}
+if ({{entry.conditions | join(' && ')}})
+    {{return_macro(entry.value)}}
+{% else %}
+if (data[{{index}}] == '{{entry.char}}')
+    {{return_macro(entry.value)}}
+{% endif %}
+return {{default_return_value}};

[Timothy Loh, 2016/05/03 07:40:25]

It might be possible to make this a "break" so we don't have to pass around
default_return_value but can just type it at the bottom of the functions in the
calling code.

[meade_UTC10, 2016/05/04 07:24:54]

Done.

+{% endmacro %}
+
+{% macro trie_switch(trie, index, return_macro, default_return_value) %}
+switch (data[{{index}}]) {
+{% for entry in trie %}
+case '{{entry.char}}':
+    {% if entry.subtrie %}
+    {{trie_switch(entry.subtrie, index + 1, return_macro, default_return_value) | indent}}
+    {% elif entry.conditions %}{# Check suffix #}
+    {{trie_leaf(index, entry, return_macro, default_return_value)}}
+    {% else %}{# Terminal node (no suffix) #}
+    {{return_macro(entry.value)}}
+    {% endif %}
+{% endfor %}
+}
+return {{default_return_value}};
+{% endmacro %}
+
+{% macro trie_length_switch(empty_case_return_value, length_tries, return_macro, default_return_value) %}
+switch (length) {
+{% if empty_case_return_value %}
+    case 0:
+        {{return_macro(empty_case_return_value)}}
+{% endif %}
+{% for length, trie in length_tries %}
+    case {{length}}:
+    {% if trie|length > 1 or trie[0].subtrie %}
+        {{trie_switch(trie, 0, return_macro, default_return_value) | indent(8)}}
+    {% else %}
+        {{trie_leaf(0, trie[0], return_macro, default_return_value) | indent(8)}}
+    {% endif %}
+{% endfor %}
+    }
+    return {{default_return_value}};
+{% endmacro %}