lib/gamnit: intro new services and refine `StringProcessor` to read model files

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>

diff --git a/lib/gamnit/model_parsers/model_parser_base.nit b/lib/gamnit/model_parsers/model_parser_base.nit
new file mode 100644 (file)
index 0000000..de0fa21
--- /dev/null
+++ b/lib/gamnit/model_parsers/model_parser_base.nit
@@ -0,0 +1,181 @@
+# This file is part of NIT ( http://www.nitlanguage.org ).
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Services to parse models from a text description
+module model_parser_base
+
+import parser_base
+
+# Vector of 3 values, either `x, y, z`, `u, v, z` or `r, g, b`
+class Vec3
+
+       # X value
+       var x = 0.0 is writable
+
+       # Y value
+       var y = 0.0 is writable
+
+       # Z value
+       var z = 0.0 is writable
+
+       # U value (redirection as `x`)
+       fun u: Float do return x
+
+       # Set U value (redirection for `x=`)
+       fun u=(value: Float) do x = value
+
+       # V value (redirection as `y`)
+       fun v: Float do return y
+
+       # Set V value (redirection for `y=`)
+       fun v=(value: Float) do y = value
+
+       # R value
+       fun r: Float do return x
+
+       # Set R value (redirection for `x=`)
+       fun r=(value: Float) do x = value
+
+       # G value
+       fun g: Float do return y
+
+       # Set G value (redirection for `y=`)
+       fun g=(value: Float) do y = value
+
+       # B value
+       fun b: Float do return z
+
+       # Set B value (redirection for `z=`)
+       fun b=(value: Float) do z = value
+
+       # Return all values into a new `Array[Float]`
+       fun to_a: Array[Float] do return [x, y, z]
+
+       redef fun to_s do return "<{class_name} {x} {y} {z}>"
+end
+
+# Vector of 4 values, either `x, y, z, w`, `u, v, z, w` or `r, g, b, a`
+class Vec4
+       super Vec3
+
+       # W value
+       var w = 1.0 is writable
+
+       # A value (redirection to `z`)
+       fun a: Float do return z
+
+       # Set A value (redirection for `z=`)
+       fun a=(value: Float) do z = value
+
+       # Return all values into a new `Array[Float]`
+       redef fun to_a do return [x, y, z, w]
+
+       redef fun to_s do return "<{class_name} {x} {y} {z} {w}>"
+end
+
+redef class StringProcessor
+       # Read a single token after skipping preceding whitespaces
+       #
+       # Returns an empty string when at `eof`
+       protected fun read_token: String
+       do
+               while not eof and src[pos].is_whitespace and src[pos] != '\n' do
+                       pos += 1
+               end
+
+               var start = pos
+               ignore_until_whitespace_or_comment
+               var ending = pos
+               var str = src.substring(start, ending-start)
+               return str
+       end
+
+       # Read 3 or 4 numbers and return them as a `Vec4`
+       #
+       # If there is no fourth value, `Vec4::w` is set to 1.0.
+       protected fun read_vec4: Vec4
+       do
+               var vec = new Vec4
+               vec.x = read_number
+               vec.y = read_number
+               vec.z = read_number
+
+               var wstr = read_token
+               if wstr.length > 0 then
+                       vec.w = if wstr.is_numeric then wstr.to_f else 0.0
+               else
+                       vec.w = 1.0
+               end
+
+               return vec
+       end
+
+       # Read 2 or 3 numbers and return them as a `Vec3`
+       #
+       # If there is no third value, `Vec3::z` is set to 0.0.
+       protected fun read_vec3: Vec3
+       do
+               var vec = new Vec3
+               vec.x = read_number
+               vec.y = read_number # Make optional
+
+               var wstr = read_token
+               if wstr.length > 0 then
+                       vec.z = if wstr.is_numeric then wstr.to_f else 0.0
+               else
+                       vec.z = 0.0
+               end
+
+               return vec
+       end
+
+       # Advance `pos` until a whitespace or `#` is encountered
+       protected fun ignore_until_whitespace_or_comment: Int
+       do
+               while src.length > pos and not src[pos].is_whitespace and src[pos] != '#' do
+                       pos += 1
+               end
+               return pos
+       end
+
+       # Read a token and parse it as a `Float`
+       protected fun read_number: Float
+       do
+               var str = read_token
+               return if str.is_numeric then str.to_f else 0.0
+       end
+
+       # Advance `pos` until the next end of line or a `#`
+       protected fun read_until_eol_or_comment: String
+       do
+               ignore_whitespaces
+               var start = pos
+               while not eof and src[pos] != '#' and src[pos] != '\n' do
+                       pos += 1
+               end
+               var ending = pos
+               var str = src.substring(start, ending-start)
+               return str.trim
+       end
+
+       # Advance `pos` to skip the next end of line
+       protected fun skip_eol
+       do
+               while not eof do
+                       var c = src.chars[pos]
+                       pos += 1
+                       if c == '\n' then break
+               end
+       end
+end